Drive apparatus

ABSTRACT

An electronic control unit ( 50, 70 ) including semiconductor modules ( 501  to  506 ) and capacitors ( 701  to  706 ) is disposed in the axial direction of a motor ( 30 ). The semiconductor modules ( 501  to  506 ) are placed longitudinally and brought into contact with a heat sink ( 601 ). The vertical line to each of surfaces of semiconductor chips included in the semiconductor modules ( 501  to  506 ) is perpendicular to the axial line of the motor ( 30 ). Accordingly, the capacitors ( 701  to  706 ) are disposed so that at least a part of the capacitors ( 701  to  706 ) overlap the semiconductor modules ( 501  to  506 ) and heat sink ( 601 ) in the axial direction of the motor ( 30 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase of International ApplicationNo. PCT/JP2010/004156 filed on Jun. 23, 2010, which designated the U.S.and claims priority to Japanese Patent Applications No. 2009-149650filed on Jun. 24, 2009, No. 2010-14393 filed on Jan. 26, 2010 and No.2010-117686 filed on May 21, 2010, the disclosures of each of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a drive apparatus, which has anelectric motor and an electronic control unit for controlling driving ofthe electric motor.

BACKGROUND ART

In recent years, as a mechanism for assisting operation of a steeringwheel of a vehicle, an electric power steering (EPS) system thatelectrically generates torque is used. In the EPS system, unlike ahydraulic system, only when a driver's steering operation is performed,the vehicle steering operation is assisted. Therefore, the EPS systemprovides many advantages such as low fuel consumption.

As a motor serving as a torque generation source of the EPS system, abrushless motor that is driven to rotate by applying, for example, athree-phase alternating current is used. When such a brushless motor isused, it is necessary to produce an alternating current (AC) output,which is out of phase with a direct current (DC) output of apredetermined voltage (for example, 12V), so as to supply windingcurrents, which are out of phase with one another, to coils of pluralphases (for example, three phases). This necessitates an electroniccontrol unit for switching the coil currents of the motor. Theelectronic control unit includes semiconductor modules that implement aswitching function.

In a conventional EPS system drive apparatus, an electronic control unitis disposed near a motor. For example, semiconductor modules aredisposed in an axial direction of the motor (patent documents No. 1 andNo. 2) or disposed around a stator included in the motor (patentdocument No. 3).

PRIOR ART DOCUMENT Patent Document

Patent document No. 1: JP-A-H10-234158

Patent document No. 2: JP-A-H10-322973

Patent document No. 3: JP-A-2004-159454

Patent document No. 4: JP-A-2002-120739

In an EPS system, a relatively large motor is employed in order toprovide sufficient torque. Therefore, the physical configuration of thesemiconductor modules gets larger. In addition, capacitors of a largephysical configuration (for example, aluminum electrolytic capacitors)are generally included in the electronic control unit for the purpose ofpreventing semiconductor chips from being broken by a surge voltagegenerated due to switching operation.

However, aside from the EPS system, various systems are incorporated ina vehicle these days. Therefore, a space wide enough to install thevarious systems is needed. The motor of the EPS system is thereforerequested to be compact.

From this viewpoint, a motor described in, for example, patent documentNo. 1 or 2, semiconductor modules and capacitors are juxtaposed in anaxial direction of the motor. As a result, the physical configuration inthe axial direction of the motor gets larger.

In a motor described in patent document No. 3, semiconductor modules aredisposed around a stator. Therefore, the physical configuration in theaxial direction of the motor is small, but the physical configuration ina radial direction of the motor is large. In addition, under a situationin which, for example, cylindrical capacitors have to be employed,though a smoothing capacitor is of a flat type, the physicalconfiguration in the radial direction gets further larger.

SUMMARY OF INVENTION

It is therefore an object of the present invention to provide asmall-sized drive apparatus having a built-in electronic control unit.

A drive apparatus according to the present invention includes a motor, aheat sink, and an electronic control unit. The motor includes acylindrical motor case that forms an outer periphery, a stator that isdisposed on the radially inner side of the motor case, and has windingswound about it to form plural phases, a rotor disposed on the radiallyinner side of the stator, and a shaft that rotates together with therotor. The heat sink is extended in the same direction as the centerline direction of the shaft from an end wall of the motor case. Theelectronic control unit is disposed on the heat sink side of the motorcase in the center line direction, and perform control of drive of themotor. The electronic control unit includes semiconductor modules thatinclude semiconductor chips for switching winding currents which flowthrough the windings of plural phases, and that is placed longitudinallyto be directly or indirectly in contact with a side wall surface of theheat sink so that the vertical line to each semiconductor chip surfaceis non-parallel to the center line of the shaft. In addition, theelectronic control unit includes capacitors connected in parallelbetween a line from supplying sides of the semiconductor modules to apower supply, and a line from grounding sides of the semiconductormodules to a ground. In the center line direction, at least parts ofrespective ranges of dispositions of the semiconductor modules, the heatsink and the capacitors overlap one another.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an electric power steering systemusing a drive apparatus according to a first embodiment of the presentinvention;

FIG. 2 is a plan view of the drive apparatus according to the firstembodiment;

FIG. 3 is a side view of the drive apparatus according to the firstembodiment;

FIG. 4 is a sectional view taken along a line 4-4 in FIG. 3;

FIG. 5 is a perspective view of the drive apparatus according to thefirst embodiment;

FIG. 6 is an exploded perspective view of the drive apparatus accordingto the first embodiment;

FIG. 7 is an explanatory diagram showing technical development towardintegration of an electronic control unit;

FIG. 8 is a plan view of a drive apparatus according to a secondembodiment;

FIG. 9 is a side view of the drive apparatus according to the secondembodiment;

FIG. 10 is a perspective view of the drive apparatus according to thesecond embodiment;

FIG. 11 is a plan view of a drive apparatus according to a thirdembodiment;

FIG. 12 is a side view of the drive apparatus according to the thirdembodiment;

FIG. 13 is a perspective view of the drive apparatus according to thethird embodiment;

FIG. 14 is a plan view of a drive apparatus according to a fourthembodiment;

FIG. 15 is a side view of the drive apparatus according to the fourthembodiment;

FIG. 16 is a perspective view of the drive apparatus according to thefourth embodiment;

FIG. 17 is a plan view of a drive apparatus according to a fifthembodiment;

FIG. 18 is a side view of the drive apparatus according to the fifthembodiment;

FIG. 19 is a perspective view of the drive apparatus according to thefifth embodiment;

FIG. 20 is a plan view of a drive apparatus according to a sixthembodiment;

FIG. 21 is a side view of the drive apparatus according to the sixthembodiment;

FIG. 22 is a perspective view of the drive apparatus according to thesixth embodiment;

FIG. 23 is a plan view of a drive apparatus according to a seventhembodiment;

FIG. 24 is a side view of the drive apparatus according to the seventhembodiment;

FIG. 25 is a perspective view of the drive apparatus according to theseventh embodiment;

FIG. 26 is a plan view of a drive apparatus according to an eighthembodiment;

FIG. 27 is a side view of the drive apparatus according to the eighthembodiment;

FIG. 28 is a perspective view of the drive apparatus according to theeighth embodiment;

FIG. 29 is a plan view of a drive apparatus according to a ninthembodiment;

FIG. 30 is a side view of the drive apparatus according to the ninthembodiment;

FIG. 31 is a perspective view of the drive apparatus according to theninth embodiment;

FIG. 32 is a plan view of a drive apparatus according to a tenthembodiment;

FIG. 33 is a side view of the drive apparatus according to the tenthembodiment;

FIG. 34 is a perspective view of the drive apparatus according to thetenth embodiment;

FIG. 35 is a plan view of a drive apparatus according to an eleventhembodiment;

FIG. 36 is a side view of the drive apparatus according to the eleventhembodiment;

FIG. 37 is a perspective view of the drive apparatus according to theeleventh embodiment;

FIG. 38 is a plan view of a drive apparatus according to a twelfthembodiment;

FIG. 39 is a side view of the drive apparatus according to the twelfthembodiment;

FIG. 40 is a perspective view of the drive apparatus according to thetwelfth embodiment;

FIG. 41 is a sectional view taken along a line 41-41 in FIG. 38;

FIG. 42 is a plan view of a drive apparatus according to a thirteenthembodiment;

FIG. 43 is a side view of the drive apparatus according to thethirteenth embodiment;

FIG. 44 is a perspective view of the drive apparatus according to thethirteenth embodiment;

FIG. 45 is a plan view of a drive apparatus according to a fourteenthembodiment;

FIG. 46 is a side view of the drive apparatus according to thefourteenth embodiment;

FIG. 47 is a perspective view of the drive apparatus according to thefourteenth embodiment;

FIG. 48 is a plan view of a drive apparatus according to a fifteenthembodiment;

FIG. 49 is a side view of the drive apparatus according to the fifteenthembodiment;

FIG. 50 is a perspective view of the drive apparatus according to thefifteenth embodiment;

FIG. 51 is a plan view of a drive apparatus according to a sixteenthembodiment;

FIG. 52 is a side view of the drive apparatus according to the sixteenthembodiment;

FIG. 53 is a perspective view of the drive apparatus according to thesixteenth embodiment;

FIG. 54 is a plan view of a drive apparatus according to a seventeenthembodiment;

FIG. 55 is a side view of the drive apparatus according to theseventeenth embodiment;

FIG. 56 is a perspective view of the drive apparatus according to theseventeenth embodiment;

FIG. 57 is a plan view of a drive apparatus according to an eighteenthembodiment;

FIG. 58 is a side view of the drive apparatus according to theeighteenth embodiment;

FIG. 59 is a perspective view of the drive apparatus according to theeighteenth embodiment;

FIG. 60 is a plan view of a drive apparatus according to a nineteenthembodiment;

FIG. 61 is a side view of the drive apparatus according to thenineteenth embodiment;

FIG. 62 is a perspective view of the drive apparatus according to thenineteenth embodiment;

FIG. 63 is a plan view of a drive apparatus according to a twentiethembodiment;

FIG. 64 is a side view of the drive apparatus according to the twentiethembodiment;

FIG. 65 is a perspective view of the drive apparatus according to thetwentieth embodiment;

FIG. 66 is a plan view of a drive apparatus according to a twenty-firstembodiment;

FIG. 67 is a side view of the drive apparatus according to thetwenty-first embodiment;

FIG. 68 is a perspective view of the drive apparatus according to thetwenty-first embodiment;

FIG. 69 is a plan view of a drive apparatus according to a twenty-secondembodiment;

FIG. 70 is a side view of the drive apparatus according to thetwenty-second embodiment;

FIG. 71 is a sectional view taken along a line 71-71 in FIG. 70;

FIG. 72 is a perspective view of the drive apparatus according to thetwenty-second embodiment;

FIG. 73 is a plan view of a drive apparatus according to a twenty-thirdembodiment;

FIG. 74 is a side view of the drive apparatus according to thetwenty-third embodiment;

FIG. 75 is a sectional view taken along a line 75-75 in FIG. 74;

FIG. 76 is a perspective view of the drive apparatus according to thetwenty-third embodiment;

FIG. 77 is a plan view of a drive apparatus according to a twenty-fourthembodiment;

FIG. 78 is a side view of the drive apparatus according to thetwenty-fourth embodiment;

FIG. 79 is a sectional view taken along a line 79-79 in FIG. 78;

FIG. 80 is a perspective view of the drive apparatus according to thetwenty-fourth embodiment;

FIG. 81 is a block diagram of an electric power steering systememploying a drive apparatus according to a twenty-fifth embodiment;

FIG. 82 is a sectional view of the drive apparatus according to thetwenty-fifth embodiment;

FIG. 83 is a plan view of the drive apparatus according to thetwenty-fifth embodiment;

FIG. 84 is a view taken in an arrow direction in FIG. 83 with a coverremoved;

FIG. 85 is an exploded perspective view of the drive apparatus accordingto the twenty-fifth embodiment;

FIG. 86 is an exploded perspective view of the drive apparatus accordingto the twenty-fifth embodiment;

FIG. 87 is a plan view of an electronic control unit of the driveapparatus according to the twenty-fifth embodiment;

FIG. 88 is a view taken in an arrow direction K88 in FIG. 87;

FIG. 89 is a view taken along an arrow direction K89 in FIG. 87;

FIG. 90 is a view taken along an arrow direction K90 in FIG. 87;

FIG. 91 is a perspective view of the electronic control unit of thedrive apparatus according to the twenty-fifth embodiment;

FIG. 92 is a plan view of the drive apparatus according to thetwenty-fifth embodiment with power modules incorporated into a heatsink;

FIG. 93 is a view taken along an arrow direction K93 in FIG. 92;

FIG. 94 is a view taken along an arrow direction K94 in FIG. 92;

FIG. 95 is a perspective view of the drive apparatus according to thetwenty-fifth embodiment with the power modules incorporated into theheat sink;

FIG. 96 is a plan view of a power unit of the drive apparatus accordingto the twenty-fifth embodiment;

FIG. 97 is a view taken along an arrow direction K97 in FIG. 96;

FIG. 98 is a perspective view of the power unit of the drive apparatusaccording to the twenty-fifth embodiment;

FIG. 99 is an exploded perspective view of a drive apparatus accordingto a twenty-sixth embodiment; and

FIG. 100 is a perspective view of the drive apparatus according to thetwenty-sixth embodiment with power modules incorporated into a heatsink.

DESCRIPTION OF EMBODIMENTS

Embodiments of a drive apparatus having a built-in electronic controlunit according to the present invention will be described below withreference to the accompanying drawings. In each of the followingembodiments, the same or equivalent reference number is added to thesame or equivalent parts in the drawings.

First Embodiment

A drive apparatus 1 according to a first embodiment includes, as shownin FIG. 1, a motor 30, a power circuit 50, and a control circuit 70. Thedrive apparatus 1 generates rotation torque on a column shaft 92 via agear 93 fixed to the column shaft 92 that is a rotation shaft of asteering wheel 91 of a vehicle, and assists steering operation of thesteering wheel 91. More particularly, when the steering wheel 91 ismanipulated by a driver, a steering torque occurring on the column shaft92 due to the manipulation is detected by a torque sensor 94. Inaddition, vehicle speed information is acquired over a controller areanetwork (CAN) in order to assist in the driver's steering operation bythe steering wheel 91. When this kind of mechanism is utilized, not onlysteering can be assisted but also manipulations of the steering wheel 91for keeping of a lane on an expressway, guiding to a parking space in aparking lot, and other operations can be automatically controlled,though it depends on a control technique.

The motor 30 is a brushless motor that rotates the gear 93 in forwardand reverse directions. It is the power circuit 50 that feeds power tothe motor 30. The power circuit 50 includes a choke coil 52 that existson a power line led from a power supply 51, a shunt resistor 53, and twoinverter circuits 60 and 68.

The inverter circuit 60 includes seven metal-oxide semiconductorfield-effect transistors (MOSFETs) 61, 62, 63, 64, 65, 66, and 67 thatare one type of field-effect transistors. The MOSFETs 61 to 67 areswitching elements. More particularly, depending on a potential at agate, a source-drain path is turned on (conduction) or off(non-conduction). The other inverter circuit 68 has the sameconfiguration as the inverter circuit 60. Therefore, only the invertercircuit 60 will be described below.

Hereinafter, the MOSFETs 61 to 67 shall be denoted simply as FETs 61 to67. The FET 67 located closest to the shunt resistor 53 is provided forprotection from reverse connection. Specifically, when the power supplyis erroneously connected, the FET 67 prevents a reverse current fromflowing.

The drains of the three FETs 61 to 63 are connected on the side of apower line. The sources of the FETs 61 to 63 are connected to the drainsof the three remaining FETs 64 to 66. Further, the sources of the FETs64 to 66 are connected to a ground. The gates of the six FETs 61 to 66are connected to six output terminals of a pre-driver circuit 71 thatwill be described later. Nodes between pairs of upper and lower FETs 61to 66 in FIG. 1 are connected to a U-phase coil, a V-phase coil, and aW-phase coil of the motor 30, respectively.

When the FETs 61 to 66 have to be discriminated from one another, thereference numerals in FIG. 1 are used to denote the FETs as the FET(Su+)61, FET(Sv+) 62, FET(Sw+) 63, FET(Su−) 64, FET(Sv−) 65, and FET(Sw−) 66.

Between the power line for the FET(Su+) 61 and the ground for theFET(Su−) 64, an aluminum electrolytic capacitor 54 is connected inparallel. Likewise, between the power line for the FET(Sv+) 62 and theground for the FET(Sv−) 65, an aluminum electrolytic capacitor 55 isconnected in parallel. Between the power line for the FET(Sw+) 63 andthe ground for the FET(Sw−) 66, an aluminum electrolytic capacitor 56 isconnected in parallel.

The control circuit 70 includes the pre-driver circuit 71, a custom IC72, a position sensor 73 and a microcomputer 74. The custom IC 72includes as functional blocks a regulator circuit 75, a position sensorsignal amplifier circuit 76, and a detection voltage amplifier circuit77.

The regulator circuit 75 is a stabilization circuit that stabilizespower. The regulator circuit 75 stabilizes power to be supplied to therespective components. For example, the microcomputer 74 operates with astable predetermined line voltage (for example, 5V) owing to theregulator circuit 75.

A signal sent from the position sensor 73 is inputted to the positionsensor signal amplifier circuit 76. The position sensor 73 outputs, asdescribed later, a rotational position signal of the motor 30. Theposition sensor signal amplifier circuit 76 amplifies the rotationalposition signal and outputs the resultant signal to the microcomputer74.

The detection voltage amplifier circuit 77 detects a voltage across theshunt resistor 53 included in the power circuit 50, amplifies thevoltage, and outputs the resultant voltage to the microcomputer 74.

Therefore, the rotational position signal of the motor 30 and thevoltage across the shunt resistor 53 are inputted to the microcomputer74. To the microcomputer 74, a steering torque signal is inputted fromthe torque sensor 94 attached to the column shaft 92. Further, to themicrocomputer 74, vehicle speed information is inputted over a CAN.

When the steering signal and vehicle speed information are inputted tothe microcomputer 74, the microcomputer 74 controls the first invertercircuit 60 via the pre-driver circuit 71 in response to a rotationalposition signal so as to assist in steering by the steering wheel 91according to a vehicle speed. The control of the inverter circuit 60 isachieved by turning on or off the FETs 61 to 66 via the pre-drivercircuit 71. Specifically, since the gates of the six FETs 61 to 66 areconnected to the six output terminals of the pre-driver circuit 71, thegate potentials are varied by the pre-driver circuit 71.

Based on the voltage across the shunt resistor 53 inputted from thedetection voltage amplifier circuit 77, the microcomputer 74 controlsthe inverter circuit 60 so as to approximate a current, which issupplied to the motor 30, to a sine wave.

For the foregoing control of the inverter circuit 60, the choke coil 52reduces noise caused by the power supply 51. The capacitors 54 to 56store charge so as to aid power feed to the FETs 61 to 66 or suppress anoise component such as a surge voltage. Since the FET 67 for reverseconnection protection is included, even when the power supply isincorrectly connected, the capacitors 54 to 56 will not be damaged.

As described above, the power circuit 50 and control circuit 70 areprovided for controlling drive of the motor 30. The power circuit 50 andcontrol circuit 70 form an electronic circuit (electronic control unit:ECU).

The output of the motor 30 to be employed in EPS is on the order of 200W to 500 W. The percentage of an area occupied by the power circuit 50and the control circuit 70 to the entire drive apparatus 1 is on theorder of 20% to 40%. The output of the motor 30 is so large that thepower circuit 50 tends to get larger in size. 70% or more of the areaoccupied by the power circuit 50 and the control circuit 70 is an areaoccupied by the power circuit 50.

Large ones out of the components of the power circuit 50 are the chokecoil 52, the capacitors 54 to 56, and the FETs 61 to 67. The FETs 61 to67 are formed as semiconductor modules.

The FET(Su+) 61 and the FET(Su−) 64 are formed as semiconductor chips,and these semiconductor chips are resin-molded to be one semiconductormodule.

Further, the FET(Sv+) 62 and the FET(Sv−) 65 are formed as semiconductorchips, and these semiconductor chips are resin-molded to be onesemiconductor module.

Further, the FET(Sw+) 63 and the FET(Sw−) 66 are formed as semiconductorchips, and these semiconductor chips are resin-molded to be onesemiconductor module.

The first inverter circuit 60 in FIG. 1 includes three semiconductormodules. In the present embodiment, as shown in FIG. 1, a total of twoinverter circuits of the first and the second inverter circuits 60 and63 are included. This halves a current that flows into one invertercircuit 60 or 68. Due to the inclusion of the two inverter circuits 60and 68, the present embodiment includes six semiconductor modules andsix capacitors.

Next, the configuration of the drive apparatus 1 of the presentembodiment will be described below. FIG. 2 is a plan view of the driveapparatus 1, FIG. 3 is a side view in which the drive apparatus is seenin an arrow direction K in FIG. 2, FIG. 4 is a sectional view takenalong a line 4-4 in FIG. 3, FIG. 5 is a perspective view, and FIG. 6 isan exploded perspective view.

The drive apparatus 1 includes a cylindrical motor case 101, whichdefines a motor outer periphery, an end frame 102 screwed to an outputend side of the motor case 101, and a bottomed cylindrical cover 103that covers an electronic control unit.

The motor 30 includes the motor case 101, a stator 201 disposed on theradially inner side of the motor case 101, a rotor 301 disposed on theradially inner side of the stator 201, and a shaft 401 that rotatestogether with the rotor 301.

The stator 201 includes twelve salient poles 202 that jut out inradially inward directions of the motor case 101. The salient poles 202are disposed at predetermined angular intervals in the circumferentialdirection of the motor case 101. The salient pole 202 includes alaminated iron core 203 produced by stacking thin plates made of amagnetic material, and an insulator 204 that is engaged with the axiallyexternal side of the laminated core 203. Windings 205 are wound aboutthe insulator 204. Lead wires 206 through which current is supplied tothe windings 205 are led out from six parts of the windings 205. Thewindings 205 function as three-phase windings for U, V, and W phasesaccording to a mode of supplying the current to the lead wires 206. Thewindings 205 realize the three-phase windings for the U, V, and Wphases. The lead wires 206 are led out toward the electronic controlunit through six holes which are formed in an axial end of the motorcase 101.

The rotor 301 is cylindrically formed with a magnetic material, forexample, iron. The rotor 301 includes a rotor core 302 and permanentmagnets 303 disposed on the radially outer side of the rotor core 302.The permanent magnets 303 have north poles and south poles alternatelyin the circumferential direction.

The shaft 401 is fitted in a shaft hole 304 formed in the axial centerof the rotor core 302. The shaft 401 is borne in a rotatable manner by abearing 104 of the motor case 101, and a bearing 105 formed on the endframe 102. Therefore, the shaft 401 is rotatable together with the rotor301 with respect to the stator 201. Part provided with the bearing 104is a border between the electronic control unit and motor (movable part)or is an end wall 106 of the motor case 101. The shaft 401 extends fromthe end wall 106 toward the electronic control unit, and has a magnet402, which is used to detect a rotational position, at the distal end onthe electronic control unit side thereof. In the vicinity of theelectronic control unit-side distal end of the shaft 401, a resin-madeprinted circuit board 801 is disposed. The printed circuit board 801 hasa position sensor 73 (FIG. 1) in the center thereof. Accordingly, therotational position of the magnet 402, that is, the rotational positionof the shaft 401 is detected by the position sensor 73.

The seven FETs 61 to 67 (FIG. 1) included in the inverter circuit 60 ofthe power circuit 50 are formed as three semiconductor modules. Thedrive apparatus 1 of the present embodiment includes two invertercircuits 60 and 68 and therefore has six semiconductor modules.

As shown in FIG. 2, the drive apparatus 1 includes six semiconductormodules 501, 502, 503, 504, 505, and 506. For discriminating thesemiconductor modules 501 to 506 from one another, the referencenumerals in FIG. 2 are used to denote the semiconductor modules as theU1 semiconductor module 501, V1 semiconductor module 502, W1semiconductor module 503, U2 semiconductor module 504, V2 semiconductormodule 505, and W2 semiconductor module 506 respectively.

Regarding the relationship of correspondence to FIG. 1, the U1semiconductor module 501 includes the FETs 61 and 64 corresponding tothe U phase. The V1 semiconductor module 502 includes the FETs 62 and 65corresponding to the V phase. Further, the W1 semiconductor module 503includes the FETs 63 and 66 corresponding to the W phase and thereverse-connection protection FET 67. Likewise, the U2 semiconductormodule 504 includes the FETs 61 and 64 corresponding to the U phase andthe reverse-connection protection FET 67, the V2 semiconductor module505 includes the FETs 62 and 65 corresponding to the V phase, and the W2semiconductor module 506 includes the FETs 63 and 66 corresponding tothe W phase. Specifically, the three U1, V1, and W1 semiconductormodules 501 to 503 form the inverter circuit 60, and the three U2, V2,and W2 semiconductor modules 504 to 506 constitute the other invertercircuit 68.

The three U1 to W1 semiconductor modules 501 to 503 forming the invertercircuit 60, and the three U2 to W2 semiconductor modules 504 to 506 areinterconnected through bus bars 507 to form module units. The bus bars507 have an interconnecting function. In addition, a bus bar 507 afarther from the motor case 101 serves as a ground, and a bus bar 507 bcloser to the motor case 101 serves as a power line (FIG. 5). Namely,power is supplied to the semiconductor modules 501 to 506 through thebus bars 507.

FIG. 2 to FIG. 6 show configuration in which the semiconductor modules501 to 506 are incorporated, but do not show power supplyingconfiguration. In reality, a connector is attached to the cover 103, andpower is supplied to the bus bars 507 via the connector.

The semiconductor modules 501 to 506 are mounted on a heat sink 601extended in the same direction as the center line direction of the shaft401 from the end wall 106 of the motor case 101.

The heat sink 601 has, as shown in FIG. 2, two column-shaped parts, theshape on the section perpendicular to the axial direction of which is asubstantially trapezoidal shape, juxtaposed as if to sandwich the centerline of the shaft 401. Further, the heat sink 601 has a predeterminedradius portion thereof cut out so that a cylindrical space can be formedin the center. When viewed as a whole, the heat sink 601 has a thickcylindrical shape that axially looks like an octagon. The heat sink 601is not limited to the octagonal shape but may, for example, axially looklike a hexagon. The heat sink 601 includes side walls 602 that form thecolumn-shaped parts each of which is shaped to axially and sectionallylook like a trapezoid. The side walls 602 include notched portions 603and 604 that provide discontinuous parts. The heat sink 601 isintegrally formed together with the motor case 101.

The side walls 602 of the heat sink 601 include side wall surfaces 605that are flanks oriented in the radially outward directions and are madewider than flanks which adjoin the notched portions 603 and 604respectively. As for the side wall surfaces 605, six side wall surfacesin total are formed in the circumferential direction. In radially inwarddirections of the respective side wall surfaces 605, accommodationspaces 606 that open onto the cylindrical space in the center areformed. The accommodation spaces 606 have arc surfaces in line with thecontours of capacitors. The accommodation spaces 606 are formed atpositions at which the accommodation spaces are opposed to the side wallsurfaces 605. In the heat sink 601, regions having the accommodationspaces 606 formed therein are made thin. However, parts from theaccommodation spaces 606 to the end wall 106 of the motor case 101 areformed as thick parts 107 that are as thick as the other part having noaccommodation spaces (FIG. 4).

As for the heat sink 601, the semiconductor modules 501 to 506 aredisposed one by one on the side wall surfaces 605 that are oriented inthe radially outward directions. Each of the semiconductor modules 501to 506 is shaped like a plate spread in the direction of the surfaces ofthe semiconductor chips that are molded. One of the surfaces of thesemiconductor module having a relatively large surface area serves as aheat radiation surface (the same will apply to embodiments to bedescribed later). For example, on the heat radiation surface, a metalsuch as copper is bared. The semiconductor modules 501 to 506 aredisposed in such a manner that the heat radiation surfaces thereof canbe in contact with the respective side wall surfaces 605. Here, the sidewall surfaces 605 are realized with planes, and the heat radiationsurfaces of the semiconductor modules 501 to 506 are planar accordingly.Insulation sheets may be interposed between the respective heatradiation surfaces of the semiconductor modules 501 to 506 and therespective side wall surfaces 605 of the heat sink 601.

Since the semiconductor modules 501 to 506 are, as described above,disposed on the side wall surfaces 605 of the heat sink 601, thevertical line V to the planes of the semiconductor chips S isperpendicular to the center line of the shaft 401 (FIG. 4 and FIG. 5).Specifically, the semiconductor modules 501 to 506 are placedlongitudinally.

Each of the semiconductor modules 501 to 506 has a coil terminal 508 atthe side end thereof facing the motor case 101 (FIG. 3 and others). Thecoil terminal 508 is bent radially outward. The lead wires 206 forsupplying current to the windings 205 are led out through the six holes,which are formed in the end wall 106 of the motor case 101, toward theelectronic control unit. The lead wires 206 are lead out toaccommodation spaces present on the radially outer sides of thesemiconductor modules 501 to 506. Accordingly, in the accommodationspaces present on the radially outer side of the semiconductor modules501 to 506, the lead wires 206 and coil terminals 508 are electricallycoupled to one another so that the lead wires 206 are clamped by thecoil terminals 508.

Each of the semiconductor modules 501 to 506 has six control terminals509 and two capacitor terminals 510 at the side end surface thereofopposite to the motor case 101. The control terminals 509 are solderedwhile being inserted into through holes of the printed circuit board 801(FIG. 4). Accordingly, the semiconductor modules 501 to 506 areelectrically connected to the control circuit 70 (FIG. 1). In contrast,the capacitor terminals 510 are branched out from the power line andground respectively in the inside of each of the semiconductor modules501 to 506. The capacitor terminals 510 are bent in the radially inwarddirections. Thus, the printed circuit board 801 is disposed in a dividerspace formed between the distal end of the heat sink 601 and the cover103.

As shown in FIG. 2 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the same sides of the semiconductor modules 501to 506 as the heat sink 601 is, that is, on the radially inner sides ofthe semiconductor modules. In order to discriminate the capacitors 701to 706 from one another, the reference numerals in FIG. 2 are used todenote the capacitors as the U1 capacitor 701, V1 capacitor 702, W1capacitor 703, U2 capacitor 704, V2 capacitor 705, and W2 capacitor 706.

Regarding the relationship of correspondence to FIG. 1, the U1 capacitor701 corresponds to the capacitor 54. The V1 capacitor 702 corresponds tothe capacitor 55. The W1 capacitor 703 corresponds to the capacitor 56.Likewise, the U2 capacitor 704 corresponds to the capacitor 54, the V2capacitor 705 corresponds to the capacitor 55, and the W2 capacitor 706corresponds to the capacitor 56.

The capacitors 701 to 706 are accommodated in the accommodation spaces606 of the heat sink 601, and disposed near the semiconductor modules501 to 506 in one-to-one correspondence with the semiconductor modules501 to 506. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401 (FIG. 5). The capacitor terminals 510 of the semiconductormodules 501 to 506 are bent in the radially inward directions.Therefore, terminals of the capacitors 701 to 706 are directly coupledto the bent capacitor terminals 510.

The shaft 401 is extended toward the electronic control unit. As shownin FIG. 4 and others, the choke coil 52 is disposed with the shaft 401penetrating therethrough. The choke coil 52 is disposed in the columnarspace formed in the center of the heat sink 601. The choke coil 52 has acoil wire wound about a doughnut-shaped iron core, and the coil endthereof is led out in the radially outward direction through the notchedportion 603 of the heat sink 601 (FIG. 2).

The coil end of the choke coil 52 is coupled so that the choke coilexists on the power line (FIG. 1). However, FIG. 2 to FIG. 6 do not showpower supply configuration for the choke coil 52.

As described above, from radially outward to radially inward, thejunctions between the coil terminals 508 and lead wires 206,semiconductor modules 501 to 506, heat sink 601, capacitors 701 to 706,and choke coil 52 are disposed in this order. Thus, accommodation spacesin radial directions are efficiently utilized.

Next, the control circuit 70 will be described below. The controlcircuit 70 is formed on the printed circuit board 801 shown in FIG. 4and others. Specifically, a wiring pattern is formed in the printedcircuit board 801 through etching processing or the like, and ICs andothers forming the control circuit 70 are mounted on the printed circuitboard (ICs and other components are not shown).

The drive apparatus 1 of the present embodiment provides the followingadvantages (1) to (14) described below.

(1) The semiconductor modules 501 to 506 are disposed in the center linedirection of the shaft 401. Accordingly, the physical configuration in aradial direction can be made smaller. In addition, the semiconductormodules 501 to 506 are placed longitudinally and disposed in contactwith the side wall surfaces 605 of the heat sink 601. Further, the heatsink 601 is provided with the accommodation spaces 606, and the sixcapacitors 701 to 706 are disposed in radial directions. In other words,the heat sink 601 and capacitors 701 to 706 are disposed in the radiallyinward directions of the six semiconductor modules 501 to 506. As aresult, in the center line direction of the shaft 401, at least parts ofranges of dispositions of the semiconductor modules 501 to 506, heatsink 601, and capacitors 701 to 706 are arranged one another. Therefore,unlike a conventional configuration, the physical configuration in theaxial direction can be made smaller. As a result, the physicalconfiguration of the drive apparatus 1 can be made as small as possible.

A motor employed in EPS has developed as shown in FIG. 7. Specifically,a “separated” configuration that has a motor and an ECU separated fromeach other has initially been used, and a “combined” configurationrelieved from layout of wirings has become a mainstream. However, the“combined” configuration has the ECU placed in a parallelepiped case,and has the ECU loaded on the periphery of a motor case. In this case,the physical configuration in the axial direction gets larger. In thedrive apparatus 1 of the present embodiment, not only the semiconductormodules 501 to 506 are placed longitudinally but also accommodationspaces preserved due to the longitudinal placement are utilized. Thus,the relationship of disposition to the capacitors 701 to 706 has beendevised. Namely, the drive apparatus 1 is of a “built-in” type.

(2) The vertical line to a semiconductor chip surface of each of thesemiconductor modules 501 to 506 is perpendicular to the center line ofthe shaft 401. This further contributes to preservation of accommodationspaces in radial directions.

(3) The capacitors 701 to 706 are disposed near the semiconductormodules 501 to 506. In addition, each of the semiconductor modules 501to 506 has the capacitor terminals 510 that are terminals dedicated tothe capacitor. Each of the capacitors 701 to 706 has the terminalsthereof coupled directly to the capacitor terminals 510 withoutintervention of the printed circuit board. Accordingly, compared withwhen the semiconductor modules 501 to 506 and capacitors 701 to 706 areconnected to one another via a substrate, wirings between thesemiconductor modules 501 to 506 and capacitors 701 to 706 can be madeas short as possible. The function of the capacitors 701 to 706 can befully exhibited. In addition, since the capacitors 701 to 706 aredisposed in one-to-one correspondence with the semiconductor modules 501to 506, the capacitance of the capacitors 701 to 706 can be maderelatively small. The physical configuration of the capacitors 701 to706 can be suppressed.

(4) The heat sink 601 extended from the end wall 106 of the motor case101 in the same direction as the direction of the center line of theshaft 401 is provided. The semiconductor modules 501 to 506 are disposedon the side walls 602 of the heat sink 601. Accordingly, heat radiationfrom the semiconductor modules 501 to 506 is facilitated. The driveapparatus can be readily applied to an EPS system in which a largecurrent flows into the motor 30.

(5) Further, in the drive apparatus 1 of the present invention, thecapacitors 701 to 706 are disposed on the same sides of thesemiconductor modules 501 to 506 as the heat sink 601 is. Moreparticularly, the capacitors 701 to 706 are accommodated in theaccommodation spaces 606 formed in the heat sink 601. Therefore,accommodation spaces can be preserved in the radially outward directionsof the semiconductor modules 501 to 506. As a result, layout of wiringscan be easily achieved.

(6) The heat radiation surfaces of the semiconductor modules 501 to 506are disposed to be in contact with the side wall surfaces 605 of theheat sink 601. Accordingly, heat radiation from the semiconductormodules 501 to 506 can be further facilitated.

(7) Since the side wall surfaces 605 are planar, the heat radiationsurfaces of the semiconductor modules 501 to 506 are also planar. Thisis advantageous from the viewpoint of easiness in flattening of thesurfaces of the semiconductor modules 501 to 506.

(8) The heat sink 601 has the side walls 602 around the center line ofthe shaft 401. The choke coil 52 is disposed on the radially inner sidesof the side walls 602. Accordingly, even when the choke coil 52 having arelatively large physical configuration is employed, the physicalconfiguration of the drive apparatus 1 can be made as small as possible.

(9) The side walls 602 include the two notched portions 603 and 604respectively that provide discontinuous parts. The notched portion 603is utilized in order to lead out the coil end of the choke coil 52 in aradially outward direction. Accordingly, routing of a winding of thechoke coil 52 can be achieved easily.

(10) The semiconductor modules 501 to 506 and printed circuit board 801are juxtaposed in an axial direction. The semiconductor modules 501 to506 include the control terminals 509, and the control terminals 509 aresoldered to the printed circuit board 801. Accordingly, even when thecontrol circuit 70 is disposed independently of the semiconductormodules 501 to 506, electrical connections are achieved via the controlterminals 509. Therefore, the configuration will not be complicated.

(11) The semiconductor modules 501 to 506 have the coil terminals 508 atthe other ends on the sides thereof opposite to the printed circuitboard 801. The coil terminals 508 are electrically coupled to the leadwires 206. Thus, electrical connections to the windings 205 of thestator 201 can be relatively easily achieved.

(12) The magnet 402 is disposed at the distal end of the shaft 401. Theposition sensor 73 on the printed circuit board 301 detects therotational position of the magnet 402, whereby the rotational positionof the shaft 401 is detected. Thus, the rotational position of the motor30 can be relatively easily detected.

(13) The W1 and U2 semiconductor modules 503 and 504 each include thereverse connection protection FET 67. Therefore, even when the powersupply is incorrectly connected, the capacitors 701 to 706 can beprevented from being damaged.

(14) The semiconductor modules 501 to 506 are in correspondence to threephases of the U, V, and W phases. More particularly, the U1 and U2semiconductor modules 501 and 504 are in correspondence to the U phase,the V1 and V2 semiconductor modules 502 and 505 are in correspondence tothe V phase, and the W1 and W2 semiconductor modules 503 and 506 are incorrespondence to the W phase. Further, the U1 to W1 semiconductormodules 501 to 503, and the U2 to W2 semiconductor modules 504 to 506are interconnected through the bus bars 507 to form module units. Thus,the semiconductor modules 501 to 506 are formed as modules in units of afunction. Therefore, the configuration of the inverter circuit 60becomes simple.

Second Embodiment

A drive apparatus 2 of a second embodiment includes, as shown in FIG. 8,six semiconductor modules 501, 502, 503, 504, 505, and 506. Fordiscriminating the semiconductor modules 501 to 506 from one another,the reference numerals in FIG. 8 are used to denote them as the U1semiconductor module 501, V1 semiconductor module 502, W1 semiconductormodule 503, U2 semiconductor module 504, V2 semiconductor module 505,and W2 semiconductor module 506.

The three U1 to W1 semiconductor modules 501 to 503, and the three U2 toW2 semiconductor modules 504 to 506 are interconnected over the bus bars507 to form module units. The bus bars 507 have an interconnectingfunction and serve as a power line.

The semiconductor modules 501 to 506 are mounted on a heat sink 611extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The shape of the heat sink 611 on the section perpendicular to the axialdirection is, as shown in FIG. 8, a cylindrical shape, and has aprism-shaped space formed internally. The heat sink 611 has the sidewall 612 around the center line of the shaft 401. In this case, theexternal wall surface of the heat sink 611 forms part of the outerperiphery of the drive apparatus 2 (FIG. 9 and FIG. 10). Namely, theouter diameter of the motor case 103 in a region thereof in which thestator 201 is arranged, and the outer diameter of the heat sink 611 areidentical to each other.

The side wall 612 of the heat sink 611 has side wall surfaces 615oriented in radially inward directions. As for the side wall surfaces615, a total of six side wall surfaces are formed in the circumferentialdirection.

As for the heat sink 611, the semiconductor modules 501 to 506 aredisposed one by one on the side wall surfaces 615 that are oriented inthe radially inward directions. The semiconductor modules 501 to 506 aredisposed so that the heat radiation surfaces thereof are in contact withthe side wall surfaces 615. The side wall surfaces 615 are formed inplanes, and the heat radiation surfaces of the semiconductor modules 501to 506 are also formed in planes accordingly.

The semiconductor modules 501 to 506 are, as described above, disposedon the respective side wall surfaces 615 of the heat sink 611, wherebythe vertical line to each semiconductor chip surface is perpendicular tothe center line of the shaft 401 (FIG. 10).

Each of the semiconductor modules 501 to 506 has a coil terminal (notshown) at the side end thereof facing the motor case 101. In addition,each of the semiconductor modules 501 to 506 has six control terminals509 and two capacitor terminals 510 at the side end surface thereofopposite to the motor case 101 (FIG. 9 and FIG. 10).

As shown in FIG. 8 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 501 to506 opposite to the heat sink 611.

The capacitors 701 to 706 are disposed near the semiconductor modules501 to 506 in one-to-one correspondence with the semiconductor modules501 to 506. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, the capacitor terminals 510 of thesemiconductor modules 501 to 506 are bent in the radially inwarddirections, and terminals of the capacitors 701 to 706 are coupleddirectly to the bent capacitor terminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 10). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core.

As described above, from radially outward to radially inward, the heatsink 611, semiconductor modules 501 to 506, capacitors 701 to 706, andchoke coil 52 are disposed in this order. Thus, accommodation spaces inradial directions are efficiently utilized.

The drive apparatus 2 of the present embodiment provides the sameadvantages as the advantages (1) to (4), (6) to (8), and (10) to (14)described in relation to the first embodiment.

Especially, in the drive apparatus 2 of the second embodiment, thecapacitors 701 to 706 are disposed on the sides of the semiconductormodules 501 to 506 opposite to the heat sink 611. Therefore,accommodation spaces for the capacitors 701 to 706 need not be formed inthe heat sink 611.

Third Embodiment

A drive apparatus 3 of a third embodiment includes, as shown in FIG. 11,six semiconductor modules 511, 512, 513, 514, 515, and 516. Fordiscriminating the semiconductor modules 511 to 516 from one another,the reference numerals in FIG. 11 are used to denote them as the U1semiconductor module 511, V1 semiconductor module 512, W1 semiconductormodule 513, U2 semiconductor module 514, V2 semiconductor module 515,and W2 semiconductor module 516.

The three U1 to W1 semiconductor modules 511 to 513, and the three U2 toW2 semiconductor modules 514 to 516 are interconnected through the busbars 507 to form module units. The bus bars 507 have the interconnectingfunction and serve as the power line.

The semiconductor modules 511 to 516 are mounted on a heat sink 621extended in the same direction as the center line direction of the shaft401 from the end wall 106 of the motor case 101.

The heat sink 621 has, as shown in FIG. 11, two column-shaped parts, theshape on a section perpendicular to the axial direction of which is asubstantially semicircular shape, juxtaposed as if to sandwich thecenter line of the shaft 401. Further, the heat sink 621 has apredetermined radius portion thereof cut out so that a columnar spacecan be formed in the center thereof. When viewed as a whole, the heatsink 621 has a thick cylindrical shape, and has side walls 622 aroundthe center line of the shaft 401. The side walls 622 include two notchedportions 623 and 624 respectively that provide discontinuous parts.

The side walls 622 of the heat sink 621 have side wall surfaces 625oriented in the radially outward directions. The side wall surfaces 625are columnar peripheral surfaces. Accommodation spaces 626 that openonto the center columnar space are formed in the radially inwarddirections of the side wall surfaces 625.

As for the heat sink 621, the semiconductor modules 511 to 516 aredisposed on the side wall surfaces 625 that are oriented in the radiallyoutward directions. Herein, the semiconductor modules 511 to 516 aredisposed so that the heat radiation surfaces thereof are in contact withthe side wall surfaces 625. Here, the side wall surfaces are thecolumnar peripheral surfaces and realized with convexly curved surfaces.Accordingly, the heat radiation surfaces of the semiconductor modules511 to 516 are concavely curved surfaces.

The semiconductor modules 511 to 516 are, as described above, disposedon the side wall surfaces 625 of the heat sink 621, whereby the verticalline to each semiconductor chip surface is perpendicular to the centerline of the shaft 401.

Each of the semiconductor modules 511 to 516 has the coil terminal 508at the side end thereof facing the motor case 101. In addition, each ofthe semiconductor modules 511 to 516 has six control terminal 509 andtwo capacitor terminals 510 at the side end surface thereof opposite tothe motor case 101 (FIG. 12 and FIG. 13).

As shown in FIG. 11, six capacitors 701, 702, 703, 704, 705, and 706 aredisposed on the same sides of the semiconductor modules 511 to 516 asthe heat sink 621 is. More particularly, the capacitors are disposed inthe accommodation spaces 626 of the heat sink 621.

The capacitors 701 to 706 are disposed near the semiconductor modules511 to 516 in one-to-one correspondence with the semiconductor modules511 to 516. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, since the capacitor terminals 510 of thesemiconductor modules 511 to 516 are bent in the radially inwarddirections, terminals of the capacitors 701 to 706 are coupled directlyto the bent capacitor terminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 13). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core. The coil end of the choke coil 52 is ledout in the radially outward direction through the notched portion 623 ofthe heat sink 621 (FIG. 11).

The drive apparatus 3 of the present embodiment provides the sameadvantages as the advantages (1) to (6) and (8) to (14) of the firstembodiment.

In particular, in the drive apparatus 3, the side wall surfaces 625 ofthe heat sink 621 are the columnar peripheral surfaces, and the heatsink 621 is shaped substantially like a cylinder. Accordingly, the heatsink 621 is formed simply.

Fourth Embodiment

A drive apparatus 4 of a fourth embodiment includes, as shown in FIG.14, six semiconductor modules 521, 522, 523, 524, 525, and 526. Fordiscriminating the semiconductor modules 521 to 526 from one another,the reference numerals in FIG. 14 are used to denote them as the U1semiconductor module 521, V1 semiconductor module 522, W1 semiconductormodule 523, U2 semiconductor module 524, V2 semiconductor module 525,and W2 semiconductor module 526.

The three U1 to W1 semiconductor modules 521 to 523, and the three U2 toW2 semiconductor modules 524 to 526 are interconnected through the busbars 507 to form module units. The bus bars 507 have the interconnectingfunction.

The semiconductor modules 521 to 526 are provided on a heat sink 631extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The shape of the heat sink 631 on the section perpendicular to the axialdirection is, as shown in FIG. 14, a cylindrical shape, and a columnarspace is formed internally. The heat sink 631 has a side wall 632 aroundthe center line of the shaft 401. In this case, an external wall surfaceof the heat sink 631 forms part of the outer periphery of the driveapparatus 4 (FIG. 15 and FIG. 16).

The side wall 632 of the heat sink 631 has a side wall surface 635oriented in radially inward directions. The side wall surface 635 is acylindrical inner peripheral surface.

As for the heat sink 631, the semiconductor modules 521 to 526 aredisposed on the side wall surface 635 which is oriented in the radiallyinward directions. The semiconductor modules 521 and 526 are disposed sothat the heat radiation surfaces thereof are in contact with the sidewall surface 635. Here, the side wall surface 635 is a concavely curvedsurface, and the heat radiation surfaces of the semiconductor modules521 to 526 are convexly curved surfaces accordingly.

Since the semiconductor modules 521 to 526 are, as described above,disposed on the side wall surface 635 of the heat sink 631, the verticalline to each semiconductor chip surface is perpendicular to the centerline of the shaft 401.

Each of the semiconductor modules 521 to 526 has a coil terminal (notshown) at the side end thereof facing the motor case 101. In addition,each of the semiconductor modules 521 to 526 has six control terminals509 and two capacitor terminals 510 at the side end surface thereofopposite to the motor case 101 (FIG. 15 and FIG. 16).

As shown in FIG. 14, six capacitors 701, 702, 703, 704, 705, and 706 aredisposed on the sides of the semiconductor modules 521 to 526 oppositeto the heat sink 631.

The capacitors 701 to 706 are disposed near the semiconductor modules521 to 526 in one-to-one correspondence with the semiconductor modules521 to 526. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, since the capacitor terminals 510 of thesemiconductor modules 521 to 526 are bent in the radially inwarddirections, terminals of the capacitors 701 to 706 are coupled directlyto the bent capacitor terminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 16). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core.

The drive apparatus 4 of the fourth embodiment provides the sameadvantages as the advantages (1) to (4, (6), (8), and (10) to (14).

Especially, in the drive apparatus 4, the capacitors 701 to 706 aredisposed on the sides of the semiconductor modules 521 to 526 oppositeto the heat sink 631. Therefore, accommodation spaces for the capacitors701 to 706 need not be formed in the heat sink 631.

In addition, in the drive apparatus 4, the side wall surface 635 of theheat sink 631 is a cylindrical inner peripheral surface, and the heatsink 631 is shaped like a cylinder. Therefore, the heat sink 631 isformed simply.

Fifth Embodiment

A drive apparatus 5 of a fifth embodiment includes, as shown in FIG. 17,six semiconductor modules 531, 532, 533, 534, 535, and 536.

The semiconductor modules 531 to 536 are mounted on a heat sink 641extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The heat sink 641 has, as shown in FIG. 17, two column-shaped parts, theshape on a section perpendicular to the axial direction of which is asubstantially trapezoidal shape, juxtaposed as if to sandwich the centerline of the shaft 401. Further, the heat sink has a predetermined radiusportion thereof cut out so that a columnar space can be formed in thecenter thereof. Here, the heat sink 641 differs from the heat sink 601in the above-described embodiment (FIG. 2) in that the radially outwardwall surfaces are tilted to approach the center line of the shaft 401 asthey are distanced from the motor case 101. When the heat sink 641 isseen as a whole, the heat sink 641 is shaped like a truncated pyramidwhose bottom is located on the side of the motor case 101. The heat sink641 has side walls 642 around the center line of the shaft 401. The sidewalls 642 include two notched portions 643 and 644 respectively thatprovide discontinuous parts.

The side walls 642 of the heat sink 641 include six side wall surfaces645 that are oriented in the radially outward directions. The side wallsurfaces 645 are planar and tilted. Accommodation spaces 646 that openonto the columnar space in the center are formed in radially inwarddirections of the side wall surfaces 645.

As for the heat sink 641, the semiconductor modules 531 to 536 aredisposed on the side wall surfaces 645 that are oriented in the radiallyoutward directions. The semiconductor modules 531 to 536 are disposed sothat the heat radiation surfaces thereof are in contact with therespective side wall surfaces 645. The side wall surfaces 645 areplanar, and the heat radiation surfaces of the semiconductor modules 531to 536 are planar accordingly.

The semiconductor modules 531 to 536 are, as described above, disposedon the side wall surfaces 645 of the heat sink 641, and are thereforetilted with respect to the center line of the shaft 401.

Further, each of the semiconductor modules 531 to 536 has the coilterminal 508 at the side end thereof facing the motor case 101. Inaddition, each of the semiconductor modules 531 to 536 has six controlterminals 509 and two capacitor terminals 510 at the side end surfacethereof opposite to the motor case 101 (FIG. 18 and FIG. 19).

As shown in FIG. 17 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the same sides of the semiconductor modules 531to 536 as the heat sink 641 is. More particularly, the capacitors aredisposed in the accommodation spaces 646 of the heat sink 641.

The capacitors 701 to 706 are disposed near the semiconductor modules531 to 536 in one-to-one correspondence with the semiconductor modules531 to 536. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, the capacitor terminals 510 of thesemiconductor modules 531 to 536 are bent in the radially inwarddirections. Therefore, terminals of the capacitors 701 to 706 arecoupled directly to the bent capacitor terminals 510 (FIG. 19).

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 19). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core. The coil end of the choke coil 52 is ledout in the radially outward direction through the notched portion 643 ofthe heat sink 641 (FIG. 17).

The drive apparatus 5 of the fifth embodiment provides the sameadvantages as the advantages (1) and (3) to (13) described in relationto the first embodiment.

Especially, in the drive apparatus 5, since the semiconductor modules531 to 536 are tilted, the physical configuration in the axial directioncan be made smaller.

In addition, the side wall surfaces 645 are tilted to approach thecenter line of the shaft 401 as they are separated from the end wall 106of the motor case 101. Therefore, when the heat sink 641 is producedthrough casting processing, the processing is relatively easy to do.

Sixth Embodiment

A drive apparatus 6 of a sixth embodiment includes, as shown in FIG. 20,six semiconductor modules 531, 532, 533, 534, 535, and 536.

The semiconductor modules 531 to 536 are mounted on a heat sink 651extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The shape of the heat sink 651 on the section perpendicular to the axialdirection is, as shown in FIG. 20, a cylindrical shape, and anaccommodation spaceshaped like a truncated pyramid is formed internally.The heat sink 651 has a side wall 652 around the center line of theshaft 401. In this case, the external wall surface of the heat sink 651forms part of the outer periphery of the drive apparatus 6 (FIG. 21 andFIG. 22).

In addition, the side wall 652 of the heat sink 651 has side wallsurfaces 655 oriented in radially inward directions. As for the sidewall surfaces 655, a total of six side wall surfaces are formed in thecircumferential direction. The heat sink 651 differs from the heat sink611 (FIG. 8) in the above-described embodiment in that the side wallsurfaces 655 are tilted. More particularly, the side wall surfaces 655are tilted to recede from the center line of the shaft 401 as they aredistanced from the end wall 106 of the motor case 101.

As for the heat sink 651, the semiconductor modules 531 to 536 aredisposed one by one on the side wall surfaces 655 that are oriented inthe radially inward directions. The semiconductor modules 531 to 536 aredisposed so that the heat radiation surfaces thereof are in contact withthe respective side wall surfaces 655. Here, the side wall surfaces 655are provided with planes, and the heat radiation surfaces of thesemiconductor modules 531 to 536 are planar accordingly.

The semiconductor modules 531 to 536 are, as described above, disposedon the respective side wall surfaces 655 of the heat sink 651, wherebythe semiconductor modules are tilted with respect to the center line ofthe shaft 401.

Each of the semiconductor modules 531 to 536 has the coil terminal 508at the side end thereof facing the motor case 101 (FIG. 20). Further,each of the semiconductor modules 531 to 536 has six control terminals509 and two capacitor terminals 510 at the side end surface thereofopposite to the motor case 101 (FIG. 21 and FIG. 22).

As shown in FIG. 20 and others, six capacitors 701, 702, 703, 704, 705,706 are disposed on the sides of the semiconductor modules 531 to 536opposite to the heat sink 651.

The capacitors 701 to 706 are disposed near the semiconductor modules531 to 536 in one-to-one correspondence with the semiconductor modules531 to 536. The capacitors 701 to 706 are in a columnar shape, and aretilted along the semiconductor modules. In addition, since the capacitorterminals 510 of the semiconductor modules 531 to 536 are bent in theradially inward directions, terminals of the capacitors 701 to 706 arecoupled directly to the bent capacitor terminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 22). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core.

The drive apparatus 6 of the sixth embodiment provides the sameadvantages as the advantages (1), (3), (4), (6) to (8), and (10) to (13)of the first embodiment.

Especially, in the drive apparatus 6, the capacitors 701 to 706 aredisposed on the sides of the semiconductor modules 531 to 536 oppositeto the heat sink 651. This obviates necessity of forming accommodationspaces for the capacitors 701 to 706 in the heat sink 651.

In the drive apparatus 6 of the present embodiment, the semiconductormodules 531 to 536 are tilted. Therefore, the physical configuration inthe axial direction can be made smaller.

Further, the side wall surfaces 655 are tilted to recede from the centerline of the shaft 401 as they separate from the end wall 106 of themotor case 101. Therefore, when the heat sink 651 is formed throughcasting processing, the processing is relatively easy to do.

Seventh Embodiment

A drive apparatus 7 of a seventh embodiment includes, as shown in FIG.23, six semiconductor modules 541, 542, 543, 544, 545, and 546.

The semiconductor modules 541 to 546 are mounted on a heat sink 661extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The heat sink 661 has, as shown in FIG. 23, two column-shaped parts, theshape on a section perpendicular to the axial direction of which is asubstantially semicircular shape, juxtaposed as if to sandwich thecenter line of the shaft 401. Further, the heat sink 661 has apredetermined radius portion thereof cut out so that a columnar spacecan be provided in the center. Here, the heat sink 661 differs from theheat sink 621 of the above-described embodiment (FIG. 11) in that theradially outward wall surfaces are tilted to approach the center line ofthe shaft 401 as they are distanced from the motor case 101. When theheat sink 661 is seen as a whole, the heat sink is shaped like atruncated pyramid whose bottom is located on the side of the motor case101. The heat sink 661 has side walls 662 around the center line of theshaft 401. The side walls 662 include two notched portions 663 and 664respectively that provide discontinuous parts.

The side walls 662 of the heat sink 661 include side wall surfaces 665oriented in the radially outward directions. The side wall surfaces 665are conical peripheral surfaces and are tilted. Accommodation spaces 666that open onto the columnar space in the center are formed in theradially inward directions of the side wall surfaces 665.

As for the heat sink 661, the semiconductor modules 541 to 546 aredisposed on the side wall surfaces 665 that are oriented in the radiallyoutward directions. The semiconductor modules 541 to 546 are disposed sothat the heat radiation surfaces thereof are in contact with the sidewall surfaces 665. Here, the side wall surfaces 665 are convexly curvedsurfaces, and the heat radiation surfaces of the semiconductor modules531 to 536 are concavely curved surfaces accordingly.

In addition, since the semiconductor modules 541 to 546 are, asdescribed above, disposed on the side wall surfaces 665 of the heat sink661, the semiconductor modules are tilted with respect to the centerline of the shaft 401.

Further, each of the semiconductor modules 541 to 546 has the coilterminal 508 at the side end thereof facing the motor case 101. Inaddition, each of the semiconductor modules 541 to 546 has six controlterminals 509 and two capacitor terminals 510 at the side end surfacethereof opposite to the motor case 101 (FIG. 24 and FIG. 25).

As shown in FIG. 23 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the same sides of the semiconductor modules 541to 546 as the heat sink 661 is. More particularly, the capacitors aredisposed in the accommodation spaces 666 of the heat sink 661.

The capacitors 701 to 706 are disposed near the semiconductor modules541 to 546 in one-to-one correspondence with the semiconductor modules541 to 546. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, the capacitor terminals 510 of thesemiconductor modules 541 to 546 are bent in the radially inwarddirections. Therefore, terminals of the capacitors 701 to 706 arecoupled directly to the bent capacitor terminals 510 (FIG. 25).

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 25). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core. The coil end of the choke coil 52 is ledout in the radially outward direction through the notched portion 663 ofthe heat sink 661 (FIG. 23).

The drive apparatus 7 of the present embodiment provides the sameadvantages as the advantages (1), (3) to (6), and (8) to (13) describedin relation to the first embodiment.

Especially, in the drive apparatus 7, since the semiconductor modules541 to 546 are tilted, the physical configuration in the axial directioncan be made smaller.

When viewed as a whole, the heat sink 661 is shaped like a truncatedpyramid. In addition, the side wall surfaces 665 are tilted to approachthe center line of the shaft 401 as they separate from the end wall 106of the motor case 101. Therefore, when the heat sink 661 is formedthrough casting processing, the processing becomes relatively easy todo.

Eighth Embodiment

A drive apparatus 8 of an eighth embodiment includes, as shown in FIG.26, six semiconductor modules 531, 532, 533, 534, 535, and 536.

The semiconductor modules 531 to 536 are mounted on a heat sink 671extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The heat sink 671 has, as shown in FIG. 26, two column-shaped parts, theshape on the section perpendicular to the axial direction of which is asubstantially trapezoidal shape, juxtaposed as if to sandwich the centerline of the shaft 401. Further, the heat sink 671 has a predeterminedradius portion thereof cut out so that a columnar space can be formed inthe center. Here, the heat sink 671 differs from the heat sink 601 ofthe above-described embodiment (FIG. 2) in that the radially outwardwall surfaces are tilted to recede from the center line of the shaft 401as they separate from the motor case 101. When the heat sink 671 is seenas a whole, the heat sink is shaped like a truncated pyramid whose topsurface that is parallel to a bottom is located on the side of the motorcase 101. The heat sink 671 has side walls 672 around the center line ofthe shaft 401. The side walls 672 include two notched portions 673 and674 respectively that provide discontinuous parts.

The side walls 672 of the heat sink 671 include six side wall surfaces675 that are oriented in the radially outward directions. The side wallsurfaces 675 are tilted.

As for the heat sink 671, the semiconductor modules 531 to 536 aredisposed on the side wall surfaces 675 that are oriented in the radiallyoutward directions. The semiconductor modules 531 to 536 are disposed sothat the heat radiation surfaces thereof are in contact with the sidewall surfaces 675. Here, the side wall surfaces 675 are planar, and theheat radiation surfaces of the semiconductor modules 531 to 536 areplanar accordingly.

Since the semiconductor modules 531 to 536 are, as described above,disposed on the side wall surfaces 675 of the heat sink 671, thesemiconductor modules are tilted with respect to the center line of theshaft 401.

Further, each of the semiconductor modules 531 to 536 has the coilterminal 508 at the side end thereof facing the motor case 101 (FIG. 27and FIG. 28). In addition, each of the semiconductor modules 531 to 536has six control terminals 509 and two capacitor terminals 510 at theside end surface thereof opposite to the motor case 101 (FIG. 27 andFIG. 28).

As shown in FIG. 26 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 531 to536 opposite to the heat sink 671.

The capacitors 701 to 706 are disposed near the semiconductor modules531 to 536 in one-to-one correspondence with the semiconductor modules531 to 536. The capacitors 701 to 706 are in a columnar shape, and aretilted along the semiconductor modules 531 to 536. In addition, sincethe capacitor terminals 510 of the semiconductor modules 531 to 536 arebent in the radially outward directions, terminals of the capacitors 701to 706 are coupled directly to the bent capacitor terminals 510 (FIG.28).

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 28). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core. The coil end of the choke coil 52 is ledout in the radially outward direction through the notched portion 673 ofthe heat sink 671.

The drive apparatus 8 of the eighth embodiment provides the sameadvantages as the advantages (1), (3), (4), and (6) to (13) described inrelation to the first embodiment.

In particular, in the drive apparatus 8, since the semiconductor modules531 to 536 are tilted, the physical configuration in the axial directioncan be made smaller.

In addition, the side wall surfaces 675 of the heat sink 671 are tiltedto recede from the center line of the shaft 401 as they separate fromthe end wall 106 of the motor case 101. Therefore, a space can bepreserved on the end wall 106 of the motor case 101.

Further, in the drive apparatus 8, the capacitors 701 to 706 aredisposed on the sides of the semiconductor modules 531 to 536 oppositeto the heat sink 671. This obviates the necessity of formingaccommodation spaces for the capacitors 701 to 706 in the heat sink 671.

Ninth Embodiment

A drive apparatus 9 of a ninth embodiment includes, as shown in FIG. 29,six semiconductor modules 501, 502, 503, 504, 505, and 506. Fordiscriminating the semiconductor modules 501 to 506 from one another,the reference numerals in FIG. 29 are used to denote them as the U1semiconductor module 501, V1 semiconductor module 502, W1 semiconductormodule 503, U2 semiconductor module 504, V2 semiconductor module 505,and W2 semiconductor module 506.

Herein, the three U1 to W1 semiconductor modules 501 to 503, and thethree U2 to W2 semiconductor modules 504 to 506 are interconnectedthrough the bus bars 507 to form module units. The bus bars 507 have theinterconnecting function and serve as the power line.

In the ninth embodiment, the drive apparatus 9 does not include a heatsink.

Each of the semiconductor modules 501 to 506 has the coil terminal 508at the side end thereof facing the motor case 101. In addition, each ofthe semiconductor modules 501 to 506 has six control terminals 509 andtwo capacitor terminals 510 at the side end surface thereof opposite tothe motor case 101 (FIG. 30).

The control terminals 509 are inserted into through holes in the printedcircuit board 801, and then soldered. The semiconductor modules 501 to506 are circumferentially arranged so that the vertical line to eachsemiconductor chip surface becomes perpendicular to the center line ofthe shaft 401 and is oriented in the radial direction. The printedcircuit board 801 is, as shown in FIG. 30 and FIG. 31, screwed to thedistal ends of two spacers 681 and 682 that are set up on the motor case101 in parallel with the center line of the shaft 401. Accordingly, thesemiconductor modules 501 to 506 are positioned with respect to themotor case 101.

As shown in FIG. 29, six capacitors 701, 702, 703, 704, 705, and 706 aredisposed on the radially inner sides of the semiconductor modules 501 to506.

The capacitors 701 to 706 are disposed near the semiconductor modules501 to 506 in one-to-one correspondence with the semiconductor modules501 to 506. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, since the capacitor terminals 510 of thesemiconductor modules 501 to 506 are bent in the radially inwarddirections, terminals of the capacitors 701 to 706 are coupled directlyto the bent capacitor terminals 510.

The drive apparatus 9 of the ninth embodiment provides the sameadvantages as the advantages (1) to (3) and (10) to (14) described inrelation to the first embodiment.

Especially, the ninth embodiment is advantageous in a case where powerconsumption is limited and heat radiation from the semiconductor modules501 to 506 is limited.

Tenth Embodiment

A drive apparatus 10 of a tenth embodiment includes, as shown in FIG.32, six semiconductor modules 531, 532, 533, 534, 535, and 536. Thesemiconductor modules 531 to 536 are mounted on a heat sink 691 extendedin the same direction as the direction of the center line of the shaft401 from the end wall 106 of the motor case 101.

The heat sink 691 has, as shown in FIG. 32, two column-shaped parts, theshape on the section perpendicular to the axial direction of which is arectangular shape, juxtaposed as if to sandwich the center line of theshaft 401. The heat sink 691 has side walls 692 around the center lineof the shaft 401.

The side walls 692 of the heat sink 691 include four side wall surfaces695 that are perpendicular to the center line of the shaft 401, and areparallel to one another.

The six semiconductor modules 531 to 536 are disposed on the side wallsurfaces 695 of the heat sink 691. More particularly, four semiconductormodules in total are disposed on the two inner side wall surfaces 695out of the four side wall surfaces 695 with two of the foursemiconductor modules being on each inner side wall surface 696. Twosemiconductor modules in total are disposed on the two outer side wallsurfaces 695 with one of the two semiconductor modules being on eachouter side wall surface.

The semiconductor modules 531 to 536 are disposed so that the heatradiation surfaces thereof are in contact with the side wall surfaces695. Here, the side wall surfaces are planar, and the heat radiationsurfaces of the semiconductor modules 531 to 536 are planar accordingly.In addition, the semiconductor modules 531 to 536 are disposed so thatthe semiconductor modules on the outer sides of the side walls 692 andthe semiconductor modules on the inner sides of the side walls 692 aredeviated from each other for fear the heat radiation surfaces may beprecisely opposed to each other with each of the side walls 692 betweenthem.

In addition, each of the semiconductor modules 531 to 536 has the coilterminal 508 at the side end thereof facing the motor case 101 (FIG. 33and FIG. 34). In addition, each of the semiconductor modules 531 to 536has six control terminals 509 and two capacitor terminals 510 on theside end surface thereof opposite to the motor case 101 (FIG. 32).

As shown in FIG. 32 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 531 to536 opposite to the heat sink 691.

The capacitors 701 to 706 are disposed near the semiconductor modules531 to 536 in one-to-one correspondence with the semiconductor modules531 to 536. The capacitors 701 to 706 are in the columnar shape, and aredisposed so that the axes thereof are parallel to the center line of theshaft 401. In addition, since the capacitor terminals of thesemiconductor modules 531 to 536 are bent to the sides of thesemiconductor modules 531 to 536 opposite to the side wall surfaces 695,terminals of the capacitors 701 to 706 are coupled directly to the bentcapacitor terminals 510.

The drive apparatus 10 of the tenth embodiment provides the sameadvantages as the advantages (1) to (4), (6), (7), and (10) to (13)described in relation to the first embodiment.

Eleventh Embodiment

A drive apparatus 11 of an eleventh embodiment includes, as shown inFIG. 35, six semiconductor modules 531, 532, 533, 534, 535, and 536. Thesemiconductor modules 531 to 536 are mounted on a heat sink 901 extendedin the same direction as the direction of the center line of the shaft401 from the end wall 106 of the motor case 101.

The heat sink 901 has, as shown in FIG. 35, a side wall 902 that extendsradially from the center at intervals of 120°. The radially extendingside wall 902 has two side wall surfaces 905 on both sides thereof.Therefore, six side wall surfaces 905 in total are formed.

The six semiconductor modules 531 to 536 are disposed on the side wallsurfaces 905 of the heat sink 901.

The semiconductor modules 531 to 536 are disposed so that the heatradiation surfaces thereof are in contact with the side wall surfaces905. Here, the side wall surfaces 905 are planar, and the heat radiationsurfaces of the semiconductor modules 531 to 536 are planar accordingly.

In addition, each of the semiconductor modules 531 to 536 has the coilterminal 508 at the side end thereof facing the motor case 101. Inaddition, each of the semiconductor modules 531 to 536 has six controlterminals 509 and two capacitor terminals 510 at the side end surfacethereof opposite to the motor case 101 (FIG. 37).

As shown in FIG. 35 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 531 to536 opposite to the heat sink 641.

The capacitors 701 to 706 are disposed near the semiconductor modules531 to 536 in one-to-one correspondence with the semiconductor modules531 to 536. The capacitors 701 to 706 are in the columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, since the capacitor terminals 510 of thesemiconductor modules 531 to 536 are bent to the sides thereof oppositeto the side wall surfaces 905, terminals of the capacitors are coupleddirectly to the bent capacitor terminals 510 (FIG. 37).

The drive apparatus 11 of the eleventh embodiment provides the sameadvantages as the advantages (1) to (4), (6), (7), and (10) to (13)described in relation to the first embodiment.

Twelfth Embodiment

A drive apparatus 12 of a twelfth embodiment includes, as shown in FIG.38, six semiconductor modules 551, 552, 553, 554, 555, and 556. Fordiscriminating the semiconductor modules 551 to 556 from one another,the reference numerals in FIG. 38 are used to denote them as the U1semiconductor module 551, V1 semiconductor module 552, W1 semiconductormodule 553, U2 semiconductor module 554, V2 semiconductor module 555,and W2 semiconductor module 556.

Herein, the three U1 to W1 semiconductor modules 551 to 553, and thethree U2 to W2 semiconductor modules 554 to 556 are interconnectedthrough the bus bars 507 to form module units. The bus bars 507 have theinterconnecting function and serve as the power line.

The semiconductor modules 551 to 556 are mounted on a heat sink 911extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The shape of the heat sink 911 on the section perpendicular to the axialdirection is, as shown in FIG. 38, a cylindrical shape, and a prismaticspace is formed internally. In other words, the heat sink 911 has a sidewall 912 around the center line of the shaft 401. In this case, theexternal wall surface of the heat sink 911 forms part of the outerperiphery of the drive apparatus 12 (FIG. 39 and FIG. 40). In addition,the side wall 912 of the heat sink 911 includes side wall surfaces 915oriented in radially inward directions. As for the side wall surfaces915, a total of six side wall surfaces are formed in the circumferentialdirection.

As for the heat sink 911, the semiconductor modules 551 to 556 aredisposed one by one on the side wall surfaces 915 that are oriented inthe radially inward directions. The semiconductor modules 551 to 556 aredisposed so that the heat radiation surfaces thereof are in contact withthe side wall surfaces 915. Here, the side wall surfaces 915 are planar,and the heat radiation surfaces of the semiconductor modules 551 to 556are also planar accordingly.

Since the semiconductor modules 551 to 556 are, as described above,disposed on the side wall surfaces 915 of the heat sink 911, thevertical line to each semiconductor chip surface is perpendicular to thecenter line of the shaft 401.

In the present embodiment, a printed circuit board 802 is disposed onthe sides of the semiconductor modules 551 to 556 closer to the motorcase 110. Therefore, unlike the above-described embodiments, each of thesemiconductor modules 501 to 506 has six control terminals 509 and twocapacitor terminals 510 at the side end thereof facing the motor case101 (FIG. 40). In addition, each of the semiconductor modules 501 to 506has a coil terminal 508 at the side end surface thereof opposite to themotor case 101. Therefore, lead wires 206 from windings 205 arepenetrated through the side wall 912 of the heat sink 911, and led outto the end of the heat sink 911.

As shown in FIG. 38 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 551 to556 opposite to the heat sink 911.

The capacitors 701 to 706 are disposed near the semiconductor modules551 to 556 in one-to-one correspondence with the semiconductor modules551 to 556. The capacitors 701 to 706 are in a columnar shaft shape, andare disposed so that the axes thereof become parallel to the center lineof the shaft 401. In addition, since the capacitor terminals 510 of thesemiconductor modules 551 to 556 are bent in the radially inwarddirections, terminals of the capacitors 701 to 706 are coupled directlyto the bent capacitor terminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough. The choke coil 52 has the coil wire wound about thedoughnut-shaped iron core.

The drive apparatus 12 of the twelfth embodiment provides the sameadvantages as the advantages (1) to (4), (6) to (8), and (10) to (14)described in relation to the first embodiment.

Especially, in the drive apparatus 12, the capacitors 701 to 706 aredisposed on the sides of the semiconductor modules 551 to 556 oppositeto the heat sink 911. This obviates the necessity of formingaccommodation spaces for the capacitors 701 to 706 in the heat sink 911.

Thirteenth Embodiment

A drive apparatus 13 of a thirteenth embodiment has, as shown in FIG.42, the same configuration as the drive apparatus 2 of the secondembodiment (FIG. 8 to FIG. 10) does. Specifically, the drive apparatus13 includes six semiconductor modules 501, 502, 503, 504, 505, and 506.The semiconductor modules 501 to 506 are mounted on the heat sink 611extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101. In addition,six capacitors 701, 702, 703, 704, 705, and 706 are disposed on thesides of the semiconductor modules 501 to 506 opposite to the heat sink611. In addition, the choke coil 52 is disposed with the shaft 401penetrating therethrough.

The drive apparatus 13 differs from the drive apparatus 2 in that thepower circuit 50 is configured on the side of an output end 403 of theshaft 401.

The drive apparatus 13 of the thirteenth embodiment provides the sameadvantages as the advantages (1) to (4), (6) to (8), and (10) to (14)described in relation to the first embodiment.

Especially, in the drive apparatus 13, the capacitors 701 to 706 aredisposed on the sides of the semiconductor modules 501 to 506 oppositeto the heat sink 611. This obviates the necessity of formingaccommodation spaces for the capacitors 701 to 706 in the heat sink 611.

Fourteenth Embodiment

A drive apparatus 14 of a fourteenth embodiment has, as shown in FIG.45, nearly the same configuration as the drive apparatus 1 of the firstembodiment (FIG. 2 to FIG. 6). Specifically, the drive apparatusincludes six semiconductor modules 561, 562, 563, 564, 565, and 566. Thesemiconductor modules 561 to 566 are mounted on the heat sink 601extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101. In addition,six capacitors 701, 702, 703, 704, 705, and 706 are disposed on the samesides of the semiconductor modules 561 to 566 as the heat sink 601 is. Achoke coil 52 is disposed with the shaft 401 penetrating therethrough(FIG. 47).

The drive apparatus 14 differs from the drive apparatus 1 in theconfiguration of the semiconductor modules 561 to 566. In the presentinvention, each of the semiconductor modules 561 to 566 has, as shown inFIG. 47, ICs 567 and others mounted on a metal substrate 568. The ICs567 are formed by molding semiconductor chips with a resin.

Herein, each of the semiconductor modules 561 to 566 has a coil terminal508 on the motor case 101 side thereof, and has six control terminals509 at the side thereof opposite to the motor case 101 side (FIG. 45 andFIG. 47).

The drive apparatus 14 of the fourteenth embodiment provides the sameadvantages as the advantages (1) to (13) described in relation to thefirst embodiment.

Especially, since the metal substrate 568 is employed, the driveapparatus 14 is excellent in heat radiation performance.

Fifteenth Embodiment

A drive apparatus 15 of the fifteenth embodiment is, as shown in FIG.48, nearly the same configuration as the drive apparatus 1 of the firstembodiment (FIG. 2 to FIG. 6). Specifically, the drive apparatus 15includes six semiconductor modules 501, 502, 503, 504, 505, and 506. Thesemiconductor modules 501 to 506 are mounted on the heat sink 601extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101. In addition,six capacitors 701, 702, 703, 704, 705, and 706 are disposed on the samesides of the semiconductor modules 501 to 506 as the heat sink 601 is.

The drive apparatus 15 differs from the drive apparatus 1 in that theshaft 401 neither extends toward an electronic control unit part norpenetrates through the choke coil 52.

The drive apparatus 15 of the fifteenth embodiment provides the sameadvantages as the advantages (1) to (14) described in relation to thefirst embodiment.

Sixteenth Embodiment

A drive apparatus 16 of a sixteenth embodiment is, as shown in FIG. 51,constructed to include only one inverter circuit 60 shown in FIG. 1.Therefore, the drive apparatus 16 includes three semiconductor modules571, 572, and 573. The three semiconductor modules 571 to 573 areinterconnected through the bus bars 507 to form a module unit.

The semiconductor modules 571 to 573 are mounted on a heat sink 921extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The heat sink 921 has, as shown in FIG. 51, one column-shaped part, theshape on the section perpendicular to the axial direction of which is asubstantially trapezoidal shape, formed on one side of the center lineof the shaft 401. In addition, the heat sink 921 has a predeterminedradius portion thereof cut out from the center of the shaft 401. Theheat sink 921 has a side wall 922.

The side wall 922 includes side wall surfaces 925 oriented in theradially outward direction. The side wall surfaces 925 are planar, andthe three side wall surfaces are formed in the circumferential directionto face radially outward. Accommodation spaces 926 are formed in theradially inward directions of the respective side wall surfaces 925.

As for the heat sink 921, the semiconductor modules 571 to 573 aredisposed on the side wall surfaces 925 that are oriented in the radiallyoutward directions. The semiconductor modules 571 to 573 are disposed sothat the heat radiation surfaces thereof are in contact with the sidewall surfaces 925. Here, the side wall surfaces 925 are planar, and theheat radiation surfaces of the semiconductor modules 571 to 573 areplanar accordingly.

Since the semiconductor modules 571 to 573 are, as described above,disposed on the side wall surfaces 925 of the heat sink 921,semiconductor chip surfaces are perpendicular to the center line of theshaft 401.

Each of the semiconductor modules 571 to 573 has the coil terminal 508at the side end thereof facing the motor case 101. The coil terminals508 clamp lead wires 207 led out from three points on the end wall 106of the motor case 101, and are thus electrically coupled to the leadwires 207 (FIG. 51 and FIG. 52). In addition, each of the semiconductormodules 571 to 573 has six control terminals 509 and two capacitorterminals 510 at the side end surface thereof opposite to the motor case101 (FIG. 53).

As shown in FIG. 51 and others, three capacitors 711, 712, and 713 aredisposed on the same sides of the semiconductor modules 571 to 573 asthe heat sink 921 is. More particularly, the capacitors are disposed inthe accommodation spaces 926 of the heat sink 921.

The capacitors 711 to 713 are disposed near the semiconductor modules571 to 573 in one-to-one correspondence with the semiconductor modules571 to 573. The capacitors 711 to 713 are in a columnar shape, and aredisposed so that the axes thereof are parallel to the center line of theshaft 401. Since the capacitor terminals 510 of the semiconductormodules 571 to 573 are bent in the radially inward directions, terminalsof the capacitors 711 to 713 are coupled directly to the bent capacitorterminals 510.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 53). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core.

The drive apparatus 16 of the sixteenth embodiment provides the sameadvantages as the advantages (1) to (14) described in relation to thefirst embodiment.

Seventeenth Embodiment

A drive apparatus 17 of a seventeenth embodiment has, as shown in FIG.54, nearly the same configuration as the drive apparatus 1 of the firstembodiment (FIG. 2 to FIG. 6) does. Specifically, the drive apparatus 17includes six semiconductor modules 581, 582, 583, 584, 585, and 586. Thesemiconductor modules 581 to 586 are mounted on a heat sink 931 extendedin the same direction as the direction of the center line of the shaft401 from the end wall 106 of the motor case 101. In addition, sixcapacitors 701, 702, 703, 704, 705, and 706 are disposed on the samesides of the semiconductor modules 581 to 586 as the heat sink 931 is.

The drive apparatus 17 differs from the drive apparatus 1 in that theaxes of the capacitors 701 to 706 are perpendicular to the center lineof the shaft 401. In short, the cylindrical capacitors 701 to 706 areplaced sideways. Therefore, the heat sink 931 includes accommodationspaces 936, the shape on the section perpendicular to the axialdirection of which is a rectangular shape, at an end in the axialdirection. In this case, terminals of the capacitors 701 to 706 arecoupled directly onto the bus bars 507 serving as the power line. Inaddition, each of the end sides of the semiconductor modules 581 to 586opposite to the motor case is not provided with capacitor terminals butis provided with six control terminals 509 alone (FIG. 56).

The drive apparatus 17 of the seventeenth embodiment provides the sameadvantages as the advantages (1), (2), and (4) to (14) described inrelation to the first embodiment.

Especially, in the drive apparatus 17, the capacitors 701 to 706 areplaced sideways near the semiconductor modules 501 to 506. Therefore,although the accommodation spaces 936 are formed in the heat sink 931,it is unnecessary to dig deep in the axial direction when forming theaccommodation spaces 936 compared with when forming the accommodationspaces 606 of the above-described embodiment (FIG. 2). Therefore,degradation in heat radiation performance of the heat sink 931 can besuppressed. In addition, the capacitors 701 to 706 are coupled directlyto the bus bars 507 of the semiconductor modules 581 to 586.Accordingly, wirings between the semiconductor modules 581 to 586 andthe capacitors 701 to 706 can be made as short as possible, and thefunction of the capacitors 701 to 706 can be fully exhibited. Inaddition, since the capacitors 701 to 706 are disposed in one-to-onecorrespondence with the semiconductor modules 581 to 586, thecapacitance of the capacitors 701 to 706 can be made relatively small.Eventually, the physical configuration of the capacitors 701 to 706 canbe suppressed.

Eighteenth Embodiment

A drive apparatus 18 of an eighteenth embodiment has, as shown in FIG.57, nearly the same configuration as the drive apparatus 17 of theseventeenth embodiment (FIG. 54 to FIG. 56). Specifically, the driveapparatus 18 includes six semiconductor modules 581, 582, 583, 584, 585,and 586. The semiconductor modules 581 to 586 are mounted on a heat sink941 extended in the same direction as the direction of the center lineof the shaft 401 from the end wall 106 of the motor case 101. Inaddition, six capacitors 701, 702, 703, 704, 705, and 706 are placedsideways on the semiconductor modules 581 to 586.

The drive apparatus 18 differs from the above-described drive apparatus17 lies in a point that the capacitors 701 to 706 are disposed on thesides opposite to the heat sink 941. Specifically, the capacitors 701 to706 are disposed on the radially outer sides of the semiconductormodules 581 to 586. In this case, terminals of the capacitors 701 to 706are coupled directly to bus bars 507 serving as a power line. Each ofthe counter-motor case sides of the semiconductor modules 581 to 586 isnot provided with capacitor terminals but is provided with six controlterminals 509 alone (FIG. 59).

The drive apparatus 18 of the eighteenth embodiment provides the sameadvantages as the advantages (1), (2), and (4) to (14) described inrelation to the first embodiment.

Especially, in the drive apparatus 18, the capacitors 701 to 706 areplaced sideways near the semiconductor modules 581 to 586. In addition,the capacitors are disposed on the radially outer sides of thesemiconductor modules 581 to 586. This obviates the necessity of formingaccommodation spaces in the heat sink 941. In addition, the terminals ofthe capacitors 701 to 706 are coupled directly to the bus bars 507 ofthe semiconductor modules 581 to 586. Accordingly, wirings between thesemiconductor modules 581 to 586 and the capacitors 701 to 706 can bemade as short as possible, and the function of the capacitors 701 to 706can be fully exhibited. In addition, since the capacitors 701 to 706 aredisposed in one-to-one correspondence with the semiconductor modules 581to 586, the capacitance of the capacitors 701 to 706 can be maderelatively small. Eventually, the physical configuration of thecapacitors 701 to 706 can be suppressed.

Nineteenth Embodiment

A drive apparatus 19 of a nineteenth embodiment includes sixsemiconductor modules 591, 592, 593, 594, 595, and 596. Fordiscriminating the semiconductor modules 591 to 596 from one another,the reference numerals in FIG. 60 are used to denote them as the U1semiconductor module 591, V1 semiconductor module 592, W1 semiconductormodule 593, U2 semiconductor module 594, V2 semiconductor module 595,and W2 semiconductor module 596.

Herein, the three U1 to W1 semiconductor modules 591 to 593 and thethree U2 to W2 semiconductor modules 594 to 596 are interconnectedthrough the bus bars 507 to form module units. The bus bars 507 have theinterconnecting function and serve as the power line.

The semiconductor modules 591 to 596 are mounted on a heat sink 951extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The shape of the heat sink 951 on the section perpendicular to the axialdirection is, as shown in FIG. 60, a substantially hexagonal columnarshape, and a columnar space is formed internally. In a side wall 952 ofthe heat sink 951, a notched portion 953 realizing a discontinuous partis formed. In addition, since the shape on the section perpendicular tothe axial direction is the substantially hexagonal columnar shape, theside wall 952 has a total of six side wall surfaces 955, which areoriented in the radially outward directions, in the circumferentialdirection.

As for the heat sink 951, the semiconductor modules 591 to 596 aredisposed one by one on the side wall surfaces 955 that are oriented inthe radially outward directions. Herein, the semiconductor modules 591to 596 are disposed so that the heat radiation surfaces thereof are incontact with the side wall surfaces 955. Here, the side wall surfaces955 are realized with planes, and the heat radiation surfaces of thesemiconductor modules 591 to 596 are planar accordingly.

Since the semiconductor modules 591 to 596 are, as described above,disposed on the side wall surfaces 955 of the heat sink 951, thevertical line to each of semiconductor chip surfaces is perpendicular tothe center line of the shaft 401.

Each of the semiconductor modules 591 to 596 has capacitor terminals 510at the side end thereof facing the motor case 101. In addition, each ofthe semiconductor modules 591 to 596 has nine terminals 509 at the sideend surface thereof opposite to the motor case 101 (FIG. 62).

As shown in FIG. 60 and others, six capacitors 701, 702, 703, 704, 705,and 706 are disposed on the sides of the semiconductor modules 591 to596 opposite to the heat sink 951. Specifically, the capacitors 701 to706 are disposed on the radially outer sides of the semiconductormodules 591 to 596. The capacitors 701 to 706 are attached usingdedicated brackets 721.

The capacitors 701 to 706 are disposed near the semiconductor modules591 to 596 in one-to-one correspondence with the semiconductor modules591 to 596. The capacitors 701 to 706 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. In addition, terminals of the capacitors 701 to 706 arecoupled directly to the capacitor terminals 510 of the semiconductormodules 591 to 596.

In addition, the choke coil 52 is disposed with the shaft 401penetrating therethrough. The choke coil 52 has the coil wire woundabout a doughnut-shaped iron core. Herein, the coil end of the chokecoil 52 is led out in the radially outward direction through the notchedportion 953 of the heat sink 951 (FIG. 60).

The drive apparatus 19 of the nineteenth embodiment provides the sameadvantages as the advantages (1) to (4) and (6) to (14) described inrelation to the first embodiment.

Especially, in the drive apparatus 19, the capacitors 701 to 706 aredisposed on the radially outer sides of the semiconductor modules 591 to596. This obviates the necessity of forming accommodation spaces for thecapacitors 701 to 706 in the heat sink 951.

Twentieth Embodiment

A drive apparatus 20 of a twentieth embodiment is, as shown in FIG. 63,similar to the drive apparatus 16 of the above-described embodiment(FIG. 51 to FIG. 53), and includes only the inverter circuit 60 shown inFIG. 1. Therefore, the drive apparatus 16 includes three semiconductormodules 1001, 1002, and 1003. The three semiconductor modules 1001 to1003 are interconnected through the bus bars 507 to form a module unit.

The drive apparatus 20 differs from the drive apparatus 16 of theabove-described embodiment in that the capacitors 711, 712, and 713 areplaced sideways on the radially outer sides of the semiconductor modules1001 to 1003. Therefore, on a side wall 962 of the heat sink 961,accommodation spaces in which the capacitors 711 to 713 are accommodatedare not formed. In addition, terminals of the capacitors 711 to 713 arecoupled directly to the bus bars 507 through which the semiconductormodules 1001 to 1003 are interconnected. Therefore, the semiconductormodules 1001 to 1003 have no capacitor terminal.

The drive apparatus 20 of the twentieth embodiment provides the sameadvantages as the advantages (1) to (14) described in relation to thefirst embodiment.

Twenty-First Embodiment

A drive apparatus 21 of a twenty-first embodiment includes, as shown inFIG. 66, six semiconductor modules 1101, 1102, 1103, 1104, 1105, and1106. For discriminating the semiconductor modules 1101 to 1106 from oneanother, the reference numerals in FIG. 66 are used to denote them asthe U1 semiconductor module 1101, V1 semiconductor module 1102, W1semiconductor module 1103, U2 semiconductor module 1104, V2semiconductor module 1105, and W2 semiconductor module 1106.

The semiconductor modules 1101 to 1106 are mounted on a heat sink 971extended in the same direction as the direction of the center line ofthe shaft 401 from the end wall 106 of the motor case 101.

The heat sink 971 has, as shown in FIG. 66, two column-shaped parts, theshape on the section perpendicular to the axial direction of which is asubstantially trapezoidal shape, juxtaposed as if to sandwich the centerline of the shaft 401. Further, the heat sink 971 has a predeterminedradius portion thereof cut out so that a columnar space can be formed inthe center. The heat sink 971 has side walls 972 around the center lineof the shaft 401. The side walls 972 include two notched portions 973and 974 respectively that provide discontinuous parts.

In addition, the side walls 972 of the heat sink 971 include side wallsurfaces 975 oriented in the radially outward directions. The side wallsurfaces 971 are planar. In addition, four accommodation spaces 976,977, 978, 970 that open onto the columnar space in the center are formedin radially inward directions of the side wall surfaces 975. Moreparticularly, the side walls 972 of the heat sink 971 include twocolumn-shaped parts whose shape on the section perpendicular to theaxial direction is a trapezoidal shape. Herein, the two accommodationspaces 976 and 977 are formed in one of the column-shaped parts, and thetwo remaining accommodation spaces 978 and 979 are formed in the othercolumn-shaped part. The accommodation spaces 976 to 979 are formed sothat each of the arc-like internal surfaces thereof is located at aposition which coincides with the border between the adjoining side wallsurfaces 975.

As for the heat sink 971, the semiconductor modules 1101 to 1106 aredisposed on the side wall surfaces 975 that are oriented in the radiallyoutward directions. Herein, the semiconductor modules 1101 to 1106 aredisposed so that the heat radiation surfaces thereof are in contact withthe side wall surfaces 975. Here, the side wall surfaces 975 are planar,and the heat radiation surfaces of the semiconductor modules 1101 to1106 are planar accordingly.

In addition, since the semiconductor modules 1101 to 1106 are, asdescribed above, mounted on the side wall surfaces 975 of the heat sink971, semiconductor chip surfaces thereof are perpendicular to the centerline of the shaft 401.

Each of the semiconductor modules 1101 to 1106 has the coil terminal 508at the side end thereof facing the motor case 101. In addition, each ofthe semiconductor modules 1101 to 1106 has six control terminals 509 andthe capacitor terminal 510 or capacitor terminals 510 at the side endsurface thereof opposite to the motor case 101 (FIG. 68). Herein, eachof the U1, U2, W1, and W2 semiconductor modules 1101, 1104, 1103, and1106 has one capacitor terminal 510. In contrast, each of the V1 and V2semiconductor modules 1102 and 1105 has two capacitor terminals 510.

As shown in FIG. 66 and others, four capacitors 721, 722, 723, and 724are disposed on the same sides of the semiconductor modules 1101 to 1106as the heat sink 971 is. More particularly, the capacitors are disposedin the accommodation spaces 976 to 979 of the heat sink 971.

The capacitors 721 to 724 are disposed near the semiconductor modules1101 to 1106. The capacitors 721 to 724 are in a columnar shape, and aredisposed so that the axes thereof become parallel to the center line ofthe shaft 401. The capacitors 721 to 724 are located at positions thatare equidistant from adjoining ones of the semiconductor modules 1101 to1106. In addition, since the capacitor terminals 510 of thesemiconductor modules 1101 to 1106 are bent in the radially inwarddirections, terminals of the capacitors 721 to 724 are coupled directlyto the bent capacitor terminals 510. More particularly, the middlesemiconductor module 1102 or 1105 of the three semiconductor modules outof the semiconductor modules 1101 to 1106 interconnected through the busbars is provided with the two capacitor terminals 510 on both sides in awidth direction, and has the control terminals 509 interposed betweenthe capacitor terminals 510. The semiconductor modules 1101 and 1103 orsemiconductor modules 1104 and 1106 located on both sides of the threesemiconductor modules out of the semiconductor modules 1101 to 1106 areprovided with the one capacitor terminal 510 on one side in the widthdirection (the side close to the adjoining module).

The present embodiment is different from the other embodiments inelectric configuration. More particularly, the inverter circuit 60 shownin FIG. 1 includes three semiconductor modules and two capacitors. Thecapacitors can be connected in parallel between the power line andground for the semiconductor modules. Therefore, the inverter circuitcan be configured using two capacitors, though the capacitance of thecapacitors has to be adjusted. The inverter circuit may be configuredusing one capacitor.

The choke coil 52 is disposed with the shaft 401 penetratingtherethrough (FIG. 68). The choke coil 52 has the coil wire wound aboutthe doughnut-shaped iron core. The coil end of the choke coil 52 is ledout in the radially outward direction through the notched portion 973 ofthe heat sink 971 (FIG. 66).

The drive apparatus 21 of the twenty-first embodiment provides the sameadvantages as the advantages (1), (2), and (4) to (14) described inrelation to the first embodiment.

Especially, since the drive apparatus 21 includes the four capacitors721 to 724, only the four accommodation spaces 976 should be formed inthe heat sink 971. Eventually, degradation in heat radiation performanceof the heat sink 971 can be suppressed.

Twenty-Second Embodiment

A drive apparatus 22 of a twenty-second embodiment includes, as shown inFIG. 69, six semiconductor modules 1201, 1202, 1203, 1204, 1205, and1206. The semiconductor modules 1201 to 1206 are mounted on a heat sink941 extended in the same direction as the direction of the center lineof the shaft 401 from the end wall 106 of the motor case 101.

The heat sink 941 has, as shown in FIG. 69, two column-shaped parts, theshape on the section perpendicular to the axial direction of which is asubstantially trapezoidal shape, juxtaposed as if to sandwich the centerline of the shaft 401. Further, the heat sink 941 has a predeterminedradius portion thereof cut out so that a columnar space can be formed inthe center. The heat sink 941 has side walls 942 around the center lineof the shaft 401. The side walls 942 include two notched portions 943and 944 respectively that provide discontinuous parts. The side walls942 of the heat sink 941 include side wall surfaces 945 oriented in theradially outward directions. The side wall surfaces 945 are planar.

As for the heat sink 941, the semiconductor modules 1201 to 1206 aredisposed on the side wall surfaces 945 that are oriented in the radiallyoutward directions. Herein, the semiconductor modules 1201 to 1206 aredisposed so that the heat radiation surfaces thereof are in contact withthe side wall surfaces 945. Here, the side wall surfaces 945 are planar,and the heat radiation surfaces of the semiconductor modules 1201 to1206 are planar accordingly.

In addition, since the semiconductor modules 1201 to 1206 are, asdescribed above, disposed on the side wall surfaces 945 of the heat sink941, the semiconductor chip surfaces are perpendicular to the centerline of the shaft 401.

Further, each of the semiconductor modules 1201 to 1206 has the coilterminal 508 at the side end thereof facing the motor case 101. Inaddition, each of the semiconductor modules 1201 to 1206 has six controlterminals 509 and capacitor terminals 510 at the side end surfacethereof opposite to the motor case 101 (FIG. 69). The capacitorterminals 510 are bent radially inward, and coupled to conductivemembers 811 and 812 disposed radially inward.

In a cylindrical space formed in the center of the heat sink 941, eightcapacitors 731, 732, 733, 734, 735, 736, 737, and 738 are disposed. Moreparticularly, the capacitors are arranged around the shaft 401 along theinternal surfaces of the side walls 942 of the heat sink 941 (FIG. 71).Thus, in the present embodiment, the eight capacitors 731 to 738 areincluded for the six semiconductor modules 1201 to 1206.

The capacitor terminals 510 are coupled to the conductive members 811and 812. The conductive members 811 and 812 include thin ring-shapedannular parts 811 a and 812 a, and joint pieces 811 b and 812 b extendedfrom the annular parts in the radially outward directions. The jointpieces 811 b and 812 b are extended in parallel with each other towardthe six semiconductor modules 1201 to 1206. The conductive members 811and 812 are disposed while being insulated from each other in the axialdirection. The conductive member 811 is disposed farther away from themotor case 101, and the other conductive member 812 is disposed closerto the motor case 101.

One of terminals of each of the capacitors 731 to 738 is coupled to theconductive member 811, and the other terminal thereof is coupled to theother conductive member 812 (FIG. 69 and FIG. 72). The joint pieces 811b and 812 b of the conductive members 811 and 812 are coupled to thecapacitor terminals 510 of the semiconductor modules 1201 to 1206. Moreparticularly, ones of the capacitor terminals 510 are coupled to thejoint pieces 811 b of the conductive member 811, and the other capacitorterminals 510 are coupled to the joint pieces 812 b of the otherconductive member 812. Accordingly, via the conductive member 811, onesof the capacitor terminals 510 of the six semiconductor modules 1201 to1206 are connected to ones of the terminals of the eight capacitors 731to 738. Via the other conductive member 812, the other capacitorterminals 510 of the six semiconductor modules 1201 to 1206 areconnected to the other terminals of the eight capacitors 731 to 738.

The twenty-second embodiment is different from the other embodiments inelectric configuration. More particularly, the semiconductor modules1201 to 1206 and the eight capacitors 731 to 738 which constitute theinverter circuits 60 and 68 shown in FIG. 1 are wired equally via theconductive members 811 and 812. Unlike the other embodiments in whichthe capacitors are connected directly to the semiconductor modules,equal capacitor performance can be readily provided for thesemiconductor modules irrespective of the number of capacitors or thesize thereof. Therefore, the inverter circuit can be configured using anarbitrary number of capacitors, though adjustment of the capacitance isneeded.

The drive apparatus 22 of the twenty-second embodiment provides the sameadvantages as the advantages (1), (2), (4) to (7), and (10) to (14)described in relation to the first embodiment.

Especially, since the drive apparatus 22 includes the eight capacitors731 to 738, the physical configuration of the capacitors 731 to 738 canbe made smaller. Therefore, the capacitors can be disposed without thenecessity of forming accommodation spaces in the heat sink 941, anddegradation in heat radiation performance of the heat sink 941 can besuppressed.

Twenty-Third Embodiment

A drive apparatus 23 of a twenty-third embodiment includes, as shown inFIG. 73, six semiconductor modules 1201, 1202, 1203, 1204, 1205, and1206. The semiconductor modules 1201 to 1206 are mounted on a heat sink941 extended in the same direction as the direction of the center lineof the shaft 401 from the end wall 106 of the motor case 101.

The arrangement of the heat sink 941 and semiconductor modules 1201 to1206 is identical to that in the drive apparatus 22.

Each of the semiconductor modules 1201 to 1206 has the coil terminal 508at the side end thereof facing the motor case 101. The coil terminals508 are bent radially outward, and coupled to the lead wires 206extended from the stator 201. In addition, each of the semiconductormodules 1201 to 1206 has six control terminals 509 and capacitorterminals 510 at the side end surface thereof opposite to the motor case101 (FIG. 73). The capacitor terminals 510 are bent radially inward, andcoupled to conductive members 811 and 812 disposed radially inward.

In a cylindrical space formed in the center of the heat sink 941, twocapacitors 741 and 742 are disposed. More particularly, the capacitorsare juxtaposed on the perimeter of the shaft 401 so that they internallyabut on the ends of notched portions 943 and 944 of side walls 942 ofthe heat sink 941 (FIG. 75). Thus, in the present embodiment, the twocapacitors 741 and 742 are included for the six semiconductor modules1201 to 1206.

The capacitor terminals 510 are coupled to the conductive members 811and 812. The conductive members 811 and 812 include thin ring-shapedannular parts 811 a and 812 a, and joint pieces 811 b and 812 b extendedin the radially outward directions from the annular parts. The jointpieces 811 b and 812 b are extended in parallel with each other towardthe six semiconductor modules 1201 to 1206. The conductive members 811and 812 are disposed while being insulated from each other in an axialdirection. The conductive member 811 is disposed farther away from themotor case 101, and the other conductive member 812 is disposed closerto the motor case 101.

Ones of terminals of the capacitors 741 and 742 are coupled to theconductive member 811, and the other terminals thereof are coupled tothe other conductive member 812 (FIG. 73). The joint pieces 811 b and812 b of the conductive members 811 and 812 are coupled to the capacitorterminals 510 of the semiconductor modules 1201 to 1206. Moreparticularly, ones of the capacitor terminals 510 are coupled to thejoint pieces 811 b of the conductive member 811, and the other capacitorterminals 510 are coupled to the joint pieces 812 b of the otherconductive member 812. Accordingly, via the conductive member 811, onesof the capacitor terminals 510 of the six semiconductor modules 1201 to1206 are connected to ones of the terminals of the two capacitors 741and 742. Via the other conductive member 812, the other capacitorterminals 510 of the semiconductor modules 1201 to 1206 are connected tothe other terminals of the two capacitors 741 and 742.

The twenty-third embodiment is different from the other embodiments inelectric configuration. More particularly, the semiconductor modules1201 to 1206 and the two capacitors 741 and 742 which constitute theinverter circuits 60 and 68 shown in FIG. 1 are equally wired via theconductive members 811 and 812. Unlike the other embodiments in whichthe capacitors are directly connected to the semiconductor modules,equal capacitor performance can be readily provided for thesemiconductor modules.

The drive apparatus 23 of the twenty-third embodiment provides the sameadvantages as the advantages (1), (2), (4) to (7), and (10) to (14)described in relation to the first embodiment.

Especially, the drive apparatus 23 includes the two capacitors 741 and742. Therefore, although the physical configuration of one capacitor islarger, the number of capacitors to be employed can be made smaller. Inaddition, the capacitors can be disposed without necessity of formingaccommodation spaces in the heat sink 941. Eventually, degradation inheat radiation performance of the heat sink 941 can be suppressed.

Twenty-Fourth Embodiment

A drive apparatus 24 of a twenty-fourth embodiment includes, as shown inFIG. 77, six semiconductor modules 1201, 1202, 1203, 1204, 1205, and1206. The semiconductor modules 1201 to 1206 are mounted on a heat sink941 extended in the same direction as the direction of the center lineof the shaft 401 from the end wall 106 of the motor case 101.

The arrangement of the heat sink 941 and semiconductor modules 1201 to1206 is identical to that in the drive apparatuses 22 and 23 of theabove-described embodiments.

Each of the semiconductor modules 1201 to 1206 has the coil terminal 508at the side end thereof facing the motor case 101. The coil terminals508 are bent radially outward, and coupled to lead wires 206 coming froma stator 201. In addition, each of the semiconductor modules 1201 to1206 has six control terminals 509 and capacitor terminals 510 at theside end surface thereof opposite to the motor case 101 (FIG. 77). Thecapacitor terminals 510 are bent radially inward, and coupled to aconductive part 821 disposed radially inward.

Herein, in the center of a cylindrical space formed in the center of theheat sink 941, one capacitor 751 is disposed (FIG. 79). Thus, in thepresent embodiment, the capacitor 751 is provided for the sixsemiconductor modules 1201 to 1206.

The capacitor terminals 510 are electrically coupled to the conductivepart 821. The conductive part 821 has an annular shape, is molded with aresin, and has electrodes 821 a and 821 b that jut radially inward so asto face each other. The conductive part 821 includes joint pieces 821 cthat jut out toward the semiconductor modules 1201 to 1206 locatedradially outward. Each pair of the joint pieces 821 c juts out inparallel with each other toward each of the semiconductor modules 1201to 1206. Herein, one of the joint pieces 821 c that jut out in parallelwith each other conducts electricity to the electrode 821 a, and theother of the joint pieces 821 c that jut out in parallel with each otherconducts electricity to the other electrode 821 b.

As shown in FIG. 77, the electrode 821 a is electrically coupled to oneof the terminals of the capacitor 751, and the other electrode 821 b iselectrically coupled to the other terminal of the capacitor 751. Inaddition, ones of the pairs of joint pieces 821 c that jut in parallelwith each other are electrically coupled to ones of the capacitorterminals 510 of the semiconductor modules 1201 to 1206. Further, theothers of the pairs of joint pieces 821 c that jut in parallel with eachother are electrically coupled to the other capacitor terminals 510 ofthe semiconductor modules 1201 to 1206.

Accordingly, via the conductive part 821, ones of the capacitorterminals 510 of the six semiconductor modules 1201 to 1206 areconnected to one of the terminals of the capacitor 751, and the othercapacitor terminals 510 of the six semiconductor modules 1201 to 1206are connected to the other terminal of the capacitor 751.

The twenty-fourth embodiment is different from the other embodiments inelectrical configuration. More particularly, the two inverter circuits60 and 68 shown in FIG. 1 include six semiconductor modules and onecapacitor. The capacitor is connected in parallel between the power lineand ground for the semiconductor modules. Therefore, although adjustmentof the capacitance is needed, the two inverter circuits 60 and 68 can beconfigured using one capacitor.

The drive apparatus 24 of the twenty-fourth embodiment provides the sameadvantages as the advantages (1), (2), (4) to (7), and (10) to (14)described in relation to the first embodiment.

Especially, the drive apparatus 24 is constructed using the capacitor751 alone. Therefore, although the physical configuration of thecapacitor is the largest, the number of capacitors employed is only oneand the capacitor can be disposed without the necessity of forming anaccommodation space in the heat sink 941. Degradation in heat radiationperformance of the heat sink 941 can be suppressed.

Twenty-Fifth Embodiment

FIG. 81 to FIG. 97 show a drive apparatus 2001 of a twenty-fifthembodiment. The drive apparatus 2001 is provided in an electronic powersteering (EPS) system, and includes a motor 2002 and an electroniccontrol unit 2003. The electronic control unit 2003 serving as anelectronic controller includes, as shown in FIG. 82, a control circuitsubstrate 2040, a heat sink 2050, power modules 2060, and a powercircuit substrate 2070.

As shown in FIG. 81, the drive apparatus 2001 generates a rotationtorque on a column shaft 2006 via a gear 2007 fixed to the column shaft2006 that is a rotation shaft of a steering wheel 2005 of a vehicle, andassists steering operation by the steering wheel 2005. Moreparticularly, when the steering wheel 2005 is manipulated by a driver,steering torque induced in the column shaft 2006 by the manipulation isdetected by a torque sensor 2008. In addition, vehicle speed informationis acquired over a controller area network (CAN) that is not shown. Thedriver's steering with the steering wheel 2005 is assisted. Using thiskind of mechanism, not only assisting in steering but also automaticallycontrolling manipulation of the steering wheel 2005 for keeping aspecific lane of an expressway or guiding to a parking space in aparking lot can be achieved, though it depends on a control technique.

The motor 2002 is a brush less motor that forwardly and reverselyrotates the gear 2007. Current is supplied to the motor 2002 under thecontrol of the electronic control unit 2003, whereby the motor 2002 isdriven. The electronic control unit 2003 includes a power circuit 2100that switches driving currents and a control circuit 2090 that controlsswitching of the driving currents.

The power circuit 2100 includes a choke coil 2076 that is provided in apower line from a power supply 2075, a smoothing capacitor 2077, and two(first and second) inverter circuits 2080 and 2089. The first invertercircuit 2080 and second inverter circuit 2089 have the sameconfiguration. Herein, the inverter circuit 2080 will be describedbelow.

The inverter circuit 2080 includes metal-oxide semiconductorfield-effect transistors (MOSFETs) (hereinafter MOSs) 2081 to 2086 thatare one type of field effect transistors. The MOSs 2081 to 2086 functionas semiconductor switching elements, and the source and drain are turnedon (conduction) or off (non-conduction) depending on a gate potential.

The MOS 2081 has the drain thereof connected to a power line, and hasthe source thereof connected to the drain of the MOS 2084. The source ofthe MOS 2084 is connected to a ground. A node between the MOS 2081 andMOS 2084 is connected to the U-phase coil of the motor 2002.

The MOS 2082 has the drain thereof connected to the power line, and hasthe source thereof connected to the drain of the MOS 2085. The source ofthe MOS 2085 is connected to the ground. A node between the MOS 2082 andMOS 2085 is connected to the V-phase coil of the motor 2002.

The MOS 2083 has the drain thereof connected to the power line and hasthe source thereof connected to the drain of the MOS 2086. The source ofthe MOS 2086 is connected to the ground. A node between the MOS 2083 andMOS 2086 is connected to the W-phase coil of the motor 2002.

The inverter circuit 2080 includes power relays 2087 and 2088. The powerrelays 2087 and 2088 are realized with MOSFETs similar to the MOSs 2081to 2086, and function as semiconductor switching elements for reverseconnection protection. The power relays 2087 and 2088 are interposedbetween the MOSs 2081 to 2083 and the power supply 2075. In case ofabnormality, the power relays can cut off flow of a current to the motor2002 via the MOSs 2081 to 2086.

Shunt resistors 2099 are electrically connected between the MOSs 2084 to2086 and the ground. By detecting a voltage or current applied to any ofthe shunt resistors 2099, a current to be conducted to the U-phase coil,V-phase coil, or W-phase coil is detected.

The choke coil 2076 is electrically connected between the power supply2075 and power relay 2087. In addition, the smoothing capacitor 2077 isconnected between the power supply 2075 and ground. The choke coil 2076and smoothing capacitor 2077 form a filter circuit, and reduces noise tobe transmitted from any other device that shares the power supply 2075.In addition, the choke coil 2076 and smoothing capacitor 2077 reducenoise to be transmitted from the drive apparatus 2001 to any otherdevice that shares the power supply 2075.

Electrolytic capacitors 2078 are electrically connected between thepower sides of the MOSs 2081 to 2083 disposed on the side of the powerline and the ground sides of the MOSs 2084 to 2086 disposed on the sideof the ground. The electrolytic capacitors 2078 accumulate charges so asto aid power feed to the MOSs 2081 to 2086 or suppress a noise componentsuch as a surge voltage.

The control circuit 2090 includes pre-driver circuits 2091, a custom IC2092, a position sensor 2093 serving as a rotation detection circuit,and a microcomputer 2094. The custom IC 2092 functions as a regulatorcircuit 2095, a position sensor signal amplifier circuit 2096, and adetection voltage amplifier circuit 2097.

The regulator circuit 2095 is a stabilization circuit that stabilizespower. The regulator circuit 2095 stabilizes power to be supplied tocomponents. For example, the microcomputer 2094 operates at a stabilizedpredetermined voltage (for example, 5V) owing to the regulator circuit2095.

The position sensor signal amplifier circuit 2096 inputs a signal fromthe position sensor 2093. The position sensor 2093 detects a rotationalposition signal of the motor 2002, and the detected rotational positionsignal is sent to the position sensor signal amplifier circuit 2096. Theposition sensor signal amplifier circuit 2096 amplifies the rotationalposition signal and outputs the resultant signal to the microcomputer2094.

The detection voltage amplifier circuit 2097 detects voltages across theshunt resistors 2099, amplifies the voltages, and outputs the resultantvoltages to the microcomputer 2094.

To the microcomputer 2094, the rotational position signal of the motor2002 and the voltages across the shunt resistors 2099 are inputted. Inaddition, to the microcomputer 2094, a steering torque signal isinputted from the torque sensor 2008 fixed to the column shaft 2006.Further, to the microcomputer 2094, vehicle speed information isinputted through the CAN. When the microcomputer 2094 receives thesteering torque signal and vehicle speed information, the microcomputer2094 controls the inverter circuit 2080 via the pre-driver circuit 2091according to the rotational position signal so that steering with thesteering wheel 2005 can be assisted according to a vehicle speed. Moreparticularly, the microcomputer 2094 switches the ON and OFF states ofthe MOSs 2081 to 2086 via the pre-driver circuit 2091 so as to controlthe inverter circuit 2080. Specifically, since the gates of the six MOSs2081 to 2086 are connected to six output terminals of the pre-drivercircuit 2091, when the gate voltages are varied by the pre-drivercircuit 2091, the ON and OFF states of MOSs 2081 to 2086 are switched.

Based on the voltages across the shunt resistors 2099 inputted from thedetection voltage amplifier circuit 2097, the microcomputer 2094controls the inverter circuit 2080 so as to approximate a current, whichis supplied to the motor 2002, to a sine wave. The microcomputer 2094controls the other inverter circuit 2089 in the same manner as itcontrols the inverter circuit 2080.

Next, the configuration of the drive apparatus 2001 will be described inconjunction with FIG. 82 to FIG. 97. FIG. 82 to FIG. 86 are viewsshowing the entirety of the drive apparatus 2001, FIG. 87 to FIG. 91 areviews showing the electronic control unit 2003, FIG. 92 to FIG. 95 areviews showing a heat sink 2050 and power modules 2060, and FIG. 96 toFIG. 98 are views showing a power unit 2015.

The drive apparatus 2001 has the electronic control unit 2003 disposedat one end in the axial direction of the motor 2002, and the motor 2002and the electronic control unit 2003 are stacked.

The motor 2002 includes a motor case 2010, a stator 2020, a rotor 2030,and a shaft 2035.

The motor case 2010 is cylindrically formed with iron or the like. Anend frame 2014 made of aluminum is secured to the end of the motor case2010 opposite to the electronic control unit 2003 using screws or thelike. An opening 2011 is formed in the axial center at the side end ofthe motor case 2010 facing the electronic control unit 2003. The shaft2035 is penetrated through the opening 2011.

A resin guide 2016 is disposed at the side end of the motor case 2010facing the electronic control unit 2003. The resin guide 2016 issubstantially annularly formed, and the center part thereof is leftopen. In addition, the resin guide 2016 has six holes.

The stator 2020 is disposed in the radially inner side of the motor case2010. The stator 2020 has twelve salient poles that jut on the radiallyinner side of the motor case 2010. The salient poles are disposed atpredetermined intervals in the circumferential direction of the motorcase 2010. Each of the salient poles includes a stacked iron core formedby stacking thin plates made of a magnetic material, and an insulatorthat is engaged with the axially outer side of the laminated iron core.Windings 2026 are wound about the insulator. The windings 2026 arethree-phase windings for U, V, and W phases.

Motor wires 2027 are led out from six of the windings 2026. The motorwires 2027 are penetrated through the six holes in the resin guide 2016.Accordingly, the motor wires 2027 are positioned by the resin guide2016, and insulation of the motor wires 2027 from the motor case 2010 isensured thereby. In addition, the motor wires 2027 are led out towardthe electronic control unit 2003, passed on the radially outer sides ofthe control circuit substrate 2040 and power modules 2060, and coupledto the power circuit substrate 2070. Specifically, when viewed in theaxial direction of the motor 2002, the motor wires 2027 are disposed onthe radially outer sides of the power modules 2060.

On the radially inner side of the stator 2020, the rotor 2030 isdisposed to be rotatable relatively to the stator 2020. The rotor 2030is cylindrically formed with a magnetic material, for example, iron. Therotor 2030 includes a rotor core 2031, and permanent magnets 2032disposed on the radially outer side of the rotor core 2031. Thepermanent magnets 2032 have north poles and south poles alternatelyarrayed in the circumferential direction.

The shaft 2035 is fitted in a shaft hole 2033 formed in the axial centerof the rotor core 2031. The shaft 2035 is borne in a rotatable manner bya bearing 2012 disposed on the motor case 2010 and a bearing 2015disposed on the end frame. This makes the shaft 2035 rotatable togetherwith the rotor 2030 with respect to the stator 2020.

The shaft 2035 includes a magnet 2036 at the side end thereof facing theelectronic control unit 2003. Since the side end of the shaft 2035facing the electronic control unit 2003 is inserted into the opening2011 of the motor case 2010, the magnet 2036 disposed at the side end ofthe shaft 2035 facing the electronic control unit 2003 is bared on theelectronic control unit 2003 side. In the present embodiment, the shaft2035 is not penetrated through the control circuit substrate 2040. Themagnet 2036 is located at a position near a motor 2002-side end surface2041 of the control circuit substrate 2040 at which the magnet 2036 isopposed to the end surface 2041.

In addition, the shaft 2035 has an output end 2037 at the end on theside thereof opposite to the electronic control unit 2003.

Next, the electronic control unit 2003 will be described below.

The electronic control unit 2003 is disposed to be housed in a motorcase area that is an area defined by projecting the motor case 2010 inthe axial direction. The electronic control unit 2003 has the controlcircuit substrate 2040, the heat sink 2050 and the power modules 2060,and the power circuit substrate 2070 arranged in this order from themotor 2002 side in the axial direction.

The control circuit substrate 2040 is a four-layer substrate formedwith, for example, a glass epoxy substrate, and shaped like asubstantially rectangular plate being housed in the motor case area.Each of the four corners of the control circuit substrate 2040 has anotch 2042 formed as an escape for attaching the heat sink 2050 to themotor case 2010. In addition, the control circuit substrate 2040 isattached to the heat sink 2050 by inserting screws 2047 from the motor2002 side thereof.

Various electronic components forming the control circuit 2090 aremounted on the control circuit substrate 2040. On the end surface of thecontrol circuit substrate 2040 facing the motor 2002, the pre-drivercircuits 2091, custom IC 2092, position sensor 2093, and microcomputer2094 which are shown in FIG. 81 are mounted. The position sensor 2093 isdisposed substantially in the center of the control circuit substrate2040 and faces the magnet 2036 of the shaft 2035. Accordingly, bydetecting a change in a magnetic field induced by the magnet 2036 thatrotates together with the shaft 2035, the rotation of the shaft 2035 isdetected. In addition, in the control circuit substrate 2040, throughholes 2043 for connection to control terminals 2064 of the power modules2060 are formed along the edges on the longitudinal sides of the controlcircuit substrate 2040. In addition, a control connector 2045 is coupledto one of the lateral sides on the side of the control circuit substrate2040 opposite to the motor 2002. The control connector 2045 is disposedso that a wiring can be coupled to the control connector from theradially outer side of the motor 2002, and inputs pieces of sensorinformation sent from various sensors.

As shown in FIG. 85 and others, the heat sink 2050 includes two heatradiation blocks 2051, and a coupling part 2052 interposed between thetwo heat radiation blocks 2051. The two heat radiation blocks 2051 andcoupling part 2052 are formed as an integrated body by a materialexhibiting good thermal conductivity (for example aluminum). In thepresent embodiment, the heat radiation blocks 2051 are disposed on theradially outer side of the center line that is a virtual line drawn byextending the axial line of the shaft 2035 of the motor 2002. The heatradiation blocks 2051 function as side walls of the heat sink 2050.

As shown in FIG. 94, the heat sink 2050 is shaped to laterally look likea letter H as a whole when viewed laterally, that is, in a direction K94in FIG. 92. The heat sink 2050 is shaped to look like, as shown in FIG.92, a bracket when viewed in the axial direction of the motor 2002. Thetwo heat radiation blocks 2051 are symmetrically disposed with thecenter of the shaft 2035 as a reference. In a concave part 2053 formedby the radially inner side surfaces of the heat radiation blocks 2051and the coupling part 2052, the control connector 2045 is locked asshown in FIG. 90 and others.

As shown in FIG. 85 and others, the heat radiation blocks 2051 areshaped like wide columns. On both edges of each of the heat radiationblocks 2051, connection portions 2054 and 2055 are formed. A hole thatpenetrates in the axial direction of the motor 2002 is formed in each ofthe connection portions 2054 and 2055. A screw 2056 is inserted into theconnection portion 2054, whereby the heat radiation block is screwed tothe motor case 2010. A screw 2057 is inserted into the other connectionportion 2055, whereby the heat radiation block is screwed together witha cover 2110, which will be described later, to the motor case 2010. Theconnection portion 2054 of one of the heat radiation blocks 2051 and theconnection portion 2054 of the other heat radiation block 2051 aredisposed symmetrically with respect to the center line of the shaft2035. Likewise, the connection portion 2055 of one of the heat radiationblocks 2051 and the connection portion 2055 of the other heat radiationblock 2051 are disposed symmetrically with respect to the center line ofthe shaft 2035.

Each of the heat radiation blocks 2051 has a heat receiving surface 2059that is a wide surface formed between the connection portions 2054 and2055 on the radially outer side of the motor case 2010. The heatreceiving surface 2059 is formed in a direction of rising from the endsurface in the axial direction of the motor case 2010. In the presentembodiment, the heat receiving surface 2059 is formed substantiallyperpendicularly to an end wall 2013 in the axial direction of the motorcase 2010.

The power modules 2060 are disposed on the radially outer side of theheat sink 2050 in the motor 2002. The power modules 2060 are disposedone by one on the two heat radiation blocks 2051.

Each of the power modules 2060 includes semiconductor chips that are notshown and form MOSs which are switching elements or power relays, a moldportion 2061 with which the semiconductor chips are covered, and controlterminals 2064 and power terminals 2065 that jut out from the moldportion 2061 (FIG. 88 and others).

As shown in FIG. 88, the control terminals 2064 are formed on a firstsurface 2062 that is a surface perpendicular to the wide surface of themold portion 2061. The power terminals 2065 are formed on a secondsurface 2063 that is a surface perpendicular to the wide surface of themold portion 2061 and opposed to the first surface 2062. In the presentembodiment, the power modules 2060 are disposed along the heat receivingsurfaces 2059 of the heat sink 2050 so that the first surfaces 2062 onwhich the control terminals 2064 are formed lie on the control circuitsubstrate 2040 sides and the second surfaces 2063 on which the powerterminals 2065 are formed lie on the power circuit substrate 2070 sides.Specifically, the power modules 2060 are placed longitudinally outsidethe heat sink 2050 in the radial direction of the motor 2002. Whenviewed in the axial direction, the control terminals 2064 and powerterminals 2065 of the power modules 2060 are point-symmetric with oneanother with the center of the shaft 2035 as a reference.

The control terminals 2064 are inserted into the through holes 2043 ofthe control circuit substrate 2040, and electrically coupled to thecontrol circuit substrate 2040 by means of solder or the like. Via thecontrol terminals 2064, a control signal sent from the control circuitsubstrate 2040 is outputted to the power modules 2060. In addition, thepower terminals 2065 are inserted into through holes 2073 formed in thepower circuit substrate 2070, and electrically coupled to the powercircuit substrate 2070 by means of solder or the like. Via the powerterminals 2065, a driving current with which the motor 2002 is driven isconducted. In the present embodiment, only a small current (for example,2 A) that is as small as required to control driving of the motor 2002is conducted to the control circuit substrate 2040. In contrast, alarger current (for example, 80 A) for driving the motor 2002 isconducted to the power circuit substrate 2070. Therefore, the powerterminals 2065 are made thicker than the control terminals 2064 are.Ground terminals 2066 are made as thick as the control terminals 2064are. The ground terminals 2066 are penetrated through the mold portion2061, are coupled to the control circuit substrate 2040 and powercircuit substrate 2070, and serve as a ground of the control circuitsubstrate 2040.

A heat radiation sheet is interposed between each of the power modules2060 and the heat sink 2050. The power module 2060 is attached togetherwith the heat radiation sheet to the heat sink 2050 with screws 2069.Accordingly, the power module 2060 is fixed to the heat sink 2050 withthe heat radiation sheet between them, and has heat, which is derivedfrom conduction, dissipated to the heat sink 2050 via the heat radiationsheet. On the heat sink 2050 side of the power module 2060, part of awiring pattern is exposed from the mold portion 2061 as a metallic heatradiation part. The metallic heat radiation part is in contact with theheat sink 2050 via the heat radiation sheet, whereby heat can beefficiently dissipated. The heat radiation sheet transfers heat, whichis generated by the power module 2060, to the heat sink 2050, andensures insulation between the power module 2060 and heat sink 2050.

The power module 2060 has the semiconductor chips, shunt resistors 2099,and others mounted on a wiring pattern made of copper and covered withthe mold portion 2061 made of a resin. In the present embodiment, thetwo power modules 2060 are included in order to realize the invertercircuits 2080 and 2089 shown in FIG. 1.

The relationship between the power modules 2060 and the electriccircuits shown in FIG. 81 is described next. One of the power modules2060 corresponds to the inverter circuit 2080, and includes the MOSs2081 to 2086, power relays 2087 and 2088, and shunt resistors 2099 whichare shown in FIG. 81. In the present embodiment, the MOSs 2081 to 2086,power relays 2087 and 2088, and shunt resistors 2099 are resin-molded asone module. The other power module 2060 corresponds to the invertercircuit 2089, and includes the MOSs, power relays, and shunt resistorsforming the inverter circuit 2089. In the present embodiment, one of thepower modules 2060 corresponds to a one-system inverter circuit. Thatis, in the present embodiment, the power modules 2060 are disposedsystem by system on the heat radiation blocks 2051.

The power circuit substrate 2070 is a thick four-layer substrate with apattern copper foil that is formed with a glass epoxy substrate, and isformed like a substantially square plate to be stored in the motor casearea. The four corners of the power circuit substrate 2070 each havenotches 2071 formed in order to preserve spaces for the connectionportions 2054, 2055 of the heat sink 2050. The power circuit substrate2070 is threaded to the heat sink 2050 by inserting screws 2072 from theside thereof opposite to the motor 2002.

In the power circuit substrate 2070, power wirings by which a drivingcurrent to drive the motor 2002 is conducted are formed. In the presentembodiment, a wiring for linking the U-phase MOS 2081, V-phase MOS 2082,and W-phase MOS 2083 over the power line, a wiring for linking theU-phase MOS 2084, V-phase MOS 2085, and W-phase MOS 2086 on the ground,a wiring for linking the power relay 2088 and MOSs 2081 to 2083, and awiring for linking the power relay 2087, choke coil 2076, and smoothingcapacitor 2077 are formed on the power circuit substrate 2070.

In the power circuit substrate 2070, the through holes 2073 throughwhich the power terminals 2065 of the power modules 2060 are penetratedare formed. In addition, through holes 2074 through which the motorwires 2027 are penetrated are formed outside the through holes 2073 inthe power circuit substrate 2070. The motor wires 2027 are penetratedthrough the through holes 2074, and electrically coupled to the powercircuit substrate 2070 with solder or the like. Accordingly, the motorwires 2027 are connected to the power modules 2060 via the power circuitsubstrate 2070.

On the side surface of the power circuit substrate 2070 facing the motor2002, the choke coil 2076, smoothing capacitor 2077, electrolyticcapacitors 2078, and power connector 2079 are mounted to constitute thepower unit 2105. The power unit 2105 and power modules 2060 constitutethe power circuit 2100.

The arrangement of the power unit 2105 will be described below inconjunction with FIG. 96 to FIG. 98.

The choke coil 2076, smoothing capacitor 2077 and electrolyticcapacitors 2078, and power connector 2079 that constitute the power unit2105 are disposed in a space formed between the coupling part 2052 ofthe heat sink 2050 and the power circuit substrate 2070 and between thetwo heat radiation blocks 2051. As for these electronic components, thechoke coil 2076, smoothing capacitor 2077 and electrolytic capacitors2078, and power connector 2079 are linearly arrayed in that order fromthe control connector 2045 coupled to the control circuit substrate2040.

The choke coil 2076 is shaped like a cylinder whose length in the axialdirection is shorter than the length in the radial direction. Whenviewed in the axial direction of the motor 2002, the choke coil 2076 islocated at a position at which the choke coil does not overlap the shaft2035. The choke coil 2076 is placed longitudinally so that the axialline thereof becomes perpendicular to the center line of the shaft 2035.

The smoothing capacitor 2077 is disposed substantially in the middle ofthe four electrolytic capacitors 2078. The four electrolytic capacitors2078 are disposed mutually adjacently to surround the smoothingcapacitor 2077. The electrolytic capacitors 2078 having a largerelectrical capacitance than the smoothing capacitor 2077 does areemployed.

The power connector 2079 is disposed on the side opposite to the controlconnector 2045 coupled to the control circuit substrate 2040. The powerconnector 2079 is disposed so that a wiring can be coupled to the powerconnector from the radially outer side of the motor 2002, and isconnected to the power supply 2075. Accordingly, power is supplied tothe power circuit substrate 2070 via the power connector 2079. The powerfrom the power supply is supplied to the windings 2026 formed on thestator 2020 by way of the power connector 2079, power circuit substrate2070, power modules 2060, and motor wires 2027.

The electronic control unit 2003 is housed inside the cover 2110. Thecover 2110 is made of a magnetic material such as iron, prevents anelectric field from leaking out from the electronic control unit 2003,and also prevents dust or the like from entering the electronic controlunit 2003. The cover 2110 has substantially the same diameter as themotor case 2010 does, and is shaped like a bottomed cylinder that openson the motor 2002. The cover 2110 is attached to the motor case 2010together with the heat sink 2050 with screws 2057. The cover 2110 hasnotches 2111 at positions corresponding to the positions of theconnectors 2045 and 2079. The connectors 2045 and 2079 are exposed toface radially outward through the notches 2111. In addition, a convexpart 2018 is formed at a position on the resin guide 2016 correspondingto the position of the notch 2111 for the power connector 2079. A step2019 is formed on the resin guide 2016 so that the resin guide 2016 canbe engaged with the cover 2110.

The microcomputer 2094 on the control circuit substrate 2040 produces apulsating signal through PWM control via the pre-driver circuits 2091 soas to assist steering operation by the steering wheel 2005 according toa vehicle speed on the basis of signals sent from the position sensor2093, torque sensor 2008, and shunt resistors 2099.

The pulsating signal is outputted to the two-system inverter circuits,which include the respective power modules 2060, via the controlterminals 2064, whereby an action of switching the on and off states ofthe MOSs of the power modules 2060 is controlled. Accordingly, sine-wavecurrents that are out of phase with one another are supplied to therespective phases of the windings 2026, whereby a rotating magneticfield is induced. On receipt of the rotating magnetic field, the rotor2030 and shaft 2035 are rotated as an integrated body. With the rotationof the shaft 2035, a driving force is outputted from the output end 2037to the gear 2007 of the column shaft 2006 in order to assist in driver'ssteering by the steering wheel 2005.

Heat generated at the time if switching the MOSs of the power modules2060 is dissipated to the heat sink 2050 through the heat radiationsheets. Thus, a failure or a malfunction arising from temperature risein the power modules 2060 can be prevented.

The sizes of the stator 2020 and rotor 2030 can be arbitrarilydesignated according to a required output.

The twenty-fifth embodiment provides the same advantages as theadvantages (1), (2), (5) to (8), and (10) to (14) described in relationto the first embodiment.

In addition, in the drive apparatus 2001, the heat sink 2050 includesthe two heat radiation blocks 2051. The power modules 2060 realizing therespective inverter circuits 2080 and 2089 are disposed one by one onthe heat radiation blocks 2051. Accordingly, heat can be dissipated fromthe power modules 2060 in a well-balanced manner. In addition, since thepower modules 2060 are disposed on the two separated heat radiationblocks 2051, it does not occur that one of the power modules 2060 isaffected by heat from the other power module 2060. Further, comparedwith the configuration in which the power modules 2060 are concentratedon the same position, it is less likely that both of two systems fail atthe same time since the power modules 2060 are located at differentpositions.

In addition, in the drive apparatus 2001, the heat radiation blocks 2051are formed to have a wide columnar shape. Each of the heat radiationblocks 2051 has the connection portions 2054 and 2055 on both the edgesthereof. Each of the connection portions 2054 and 2055 has a hole thatpenetrates in the axial direction of the motor 2002. The screw 2056 isinserted into the connection portion 2054, whereby the heat radiationblock is screwed to the motor case 2010. The screw 2057 is inserted intothe other connection portion 2055, whereby the heat radiation block isscrewed together with the cover 2110 to the motor case 2010.Accordingly, the heat sink 2050 can be readily secured to the motor case2010.

Further, in the drive apparatus 2001, the two heat radiation blocks 2051are symmetrically disposed with the center of the shaft 2035 as areference. Owing to the heat radiation blocks 2051, the time requiredfor layout or design of the power modules 2060 or for attachment work isshortened.

Twenty-Sixth Embodiment

In a drive apparatus 2200 of a twenty-sixth embodiment, as shown in FIG.99 and FIG. 100, a heat sink 2250 includes, similarly to that of thetwenty-fifth embodiment, two heat radiation blocks 2251, and a couplingpart 2252 interposed between the two heat radiation blocks 2251. The twoheat radiation blocks 2251 and coupling part 2252 are formed as anintegrated body with a material of high thermal conductivity (forexample, aluminum).

Two module units 2260 and 2270 are disposed on each of the heatradiation blocks 2251. The module unit 2260 is disposed on the surfacefacing the power circuit substrate 2070. Specifically, the module unit2260 is disposed substantially horizontally with respect to the end wall2013 in the axial direction of the motor case 2010. The other moduleunit 2270 is disposed on the heat radiation block 2251 on the radiallyouter side of the motor 2002 in a direction of rising from the end wall2013 in the axial direction of the motor case 2010. That is, the moduleunit 2270 is placed longitudinally with respect to the end wall 2013 inthe axial direction of the motor case 2010.

The module unit 2260 includes four semiconductor modules 2261 to 2264and a wiring substrate 2265. Each of the semiconductor modules 2261 to2264 has three terminals 2266 attached to one surface perpendicular to awide surface thereof, and is disposed so that the terminals 2266 areoriented to the radially outer side of the motor 2002. The terminals2266 of the semiconductor modules 2261 to 2264 are bent substantiallyperpendicularly toward the power circuit substrate 2070.

The module unit 2270 includes four semiconductor modules 2271 to 2274and a wiring substrate 2275. Each of the semiconductor modules 2271 to2274 has three terminals 2276 attached to one surface perpendicular to awide surface thereof. The semiconductor modules 2271 to 2274 aredisposed so that the terminals 2276 are oriented toward the powercircuit substrate 2070.

The terminals 2266 of the semiconductor modules 2261 to 2264 and theterminals 2276 of the semiconductor modules 2271 to 2274 are insertedinto through holes 2277 formed in the power circuit substrate 2070, andelectrically connected to the power circuit substrate 2070 with solderor the like.

The module units 2260 and 2270 are attached to the heat sink 2250 withscrews 2269. A heat radiation sheet ensures insulation between themodule unit 2260 or 2270 and the heat sink 2250.

The module units 2260 and 2270 disposed on the outer side of one of theheat radiation blocks 2251 are associated with the inverter circuit2080, and the module units 2260 and 2270 disposed on the other heatradiation block 2251 are associated with the inverter circuit 2089. Theinverter circuit 2080 and inverter circuit 2089 are identical to eachother. Therefore, the module units 2260 and 2270 associated with theinverter circuit 2080 will be described below.

In the module unit 2260 disposed on the surface of one of the heatradiation blocks 2251 facing the power circuit substrate 2070, thesemiconductor module 2261 includes the power relay 2087, thesemiconductor module 2262 includes the MOS 2081, the semiconductormodule 2263 includes the MOS 2082, and the semiconductor module 2264includes the MOS 2083. That is, the module unit 2260 includes the MOSs2081 to 2083 on the side of the power line and the one power relay 2087.The module unit 2260 includes the MOSs 2081 to 2083 on the side of thepower line so as to form an upstream (high-potential) unit.

In the module unit 2270 placed longitudinally on the radially outer sidesurface of the heat radiation block 2251, the semiconductor module 2271includes the power relay 2088, the semiconductor module 2272 includesthe MOS 2084, the semiconductor module 2273 includes the MOS 2085, andthe semiconductor module 2274 includes the MOS 2086. That is, the moduleunit 2270 includes the MOSs 2084 to 2086 on the side of a ground and theone power relay 2088. The module unit 2270 includes the MOSs 2084 to2086 on the side of the ground so as to realize a downstream(low-potential) unit.

Specifically, the semiconductor module 2262 including the MOS 2081connected to the U-phase coil and the semiconductor module 2272including the MOS 2084 connected to the U-phase coil are disposed toadjoin through a side line of the heat radiation block 2251, which liesbetween two surfaces of the power circuit substrate 2070 side and theradially outer side. Likewise, the semiconductor module 2263 includingthe MOS 2082 connected to the V-phase coil and the semiconductor module2273 including the MOS 2085 connected to the V-phase coil are disposedto adjoin through the side line of the heat radiation block 2251, whichlies between the two surfaces of the radially outer side and the powercircuit substrate 2070 side. In addition, the semiconductor module 2264including the MOS 2083 connected to the W-phase coil and thesemiconductor module 2274 including the MOS 2086 connected to theW-phase coil are disposed to adjoin through the side line of the heatradiation block 2251, which lies between the two surfaces of theradially outer side and the power circuit substrate 2070 side. Further,the semiconductor module 2261 including the power relay 2087 and thesemiconductor module 2271 including the power relay 2088 are disposed toadjoin through the side line of the heat radiation block 2251, whichlies between two surfaces of the radially outer side and the powercircuit substrate 2070 side. Since the semiconductor modules are thusdisposed, a wiring loss can be minimized.

In the twenty-sixth embodiment, the semiconductor modules 2261 to 2264and 2271 to 2274 are devoid of a terminal for direct connection to thecontrol circuit substrate 2040. Therefore, the control circuit substrate2040 and power circuit substrate 2070 are electrically connected to eachother by a substrate connection terminal 2278. The control circuitsubstrate 2040 and the semiconductor modules 2261 to 2264 and 2271 to2274 are electrically connected to one another via the substrateconnection terminal 2278 and power circuit substrate 2070. A controlsignal outputted from the control circuit substrate 2040 is sent to thesemiconductor modules 2261 to 2264 and 2271 to 2274 by way of thesubstrate connection terminal 2278 and power circuit substrate 2070,whereby turning on or off the MOSs of the semiconductor modules 2261 to2264 and 2271 to 2274 is controlled. Therefore, drive of the motor 2002is controlled in the same manner as it is in the twenty-fifthembodiment.

According to the twenty-sixth embodiment provides the same advantages asthose of the twenty-fifth embodiment.

In the twenty-sixth embodiment, unlike the twenty-fifth embodiment,systematically integrated modules are not employed but the semiconductormodules 2261 to 2264 and 2271 to 2274 that are resin-molded in units ofeach MOS are employed. The semiconductor modules 2261 to 2264 and 2271to 2274 are disposed on the surface of the heat sink 2250 facing thepower circuit substrate 2070. This permits effective utilization of aspace and contributes to compactness of the entire device.

The present invention is not limited to the above-described embodimentsbut may be implemented in other various modes.

(A) The embodiments are described as being used for EPS. A driveapparatus having the similar configuration can be adapted to any otherfield.

(B) In the above-described embodiments, the semiconductor modules aredisposed on plural side wall surfaces of the heat sink. Alternatively,the semiconductor modules may be disposed on a single side wall surfaceof the heat sink.

(C) In the above-described embodiments, the doughnut-shaped choke coil52 is inserted over the shaft 401. The choke coil is not limited to thedoughnut shape. In addition, the choke coil may not be inserted over theshaft 401 but may be disposed around the shaft 401. Here, the coil maybe placed longitudinally or sideways.

(D) In the above-described embodiments, the board surface of the printedcircuit board 801 or 802 is perpendicular to the center line of theshaft 401. However, the present invention is not limited to thisperpendicular arrangement. In addition, although the printed circuitboard 801 or 802 is used, it is possible to use no circuit board.

(E) In the above-described embodiments, the cover 103 is included.Alternatively, it is possible to use no cover.

(F) In the above-described embodiments, the coil terminals 508, controlterminals 509, and capacitor terminals 510 jut out from the ends in theaxial direction of the semiconductor modules. In contrast, the terminals508, 509, and 510 may jut out from the ends of the semiconductor modulesoriented in any direction other than the axial direction.

(G) In the above-described embodiments, the magnet 402 fixed to theshaft 401 and the position sensor 73 mounted on the printed circuitboard 801 are used to detect a rotational position. Alternatively, anyother method may be used to detect the rotational position.

(H) In the above-described embodiments, the heat sink is integrallyformed with the motor case. The heat sink may be formed separately fromthe motor case.

(I) In the above-described embodiments, the capacitors are disposed nearrespective semiconductor modules. Alternatively, the capacitors may bedisposed so that a range of disposition in an axial direction of thecapacitors is partly superposed on the range of disposition in the axialdirection of the semiconductor modules. In addition, the aluminumelectrolytic capacitor of columnar shape is used. If a large capacitanceis not needed, any other type of capacitor may be used.

The invention claimed is:
 1. A drive apparatus comprising: a motorincluding a cylindrical motor case that forms an outer periphery, astator that is disposed on a radially inner side of the motor case andhas windings wound about the stator to form a plurality of phases, arotor disposed on a radially inner side of the stator, and a shaft thatrotates together with the rotor; a heat sink extended in a samedirection as a center line direction of the shaft from an end wall ofthe motor case; and an electronic control unit that is disposed on aheat sink side in the center line direction of the motor case, andperforms control of drive of the motor, wherein the electronic controlunit includes: semiconductor modules that include semiconductor chipsfor switching winding currents which flow through the windings of theplurality of phases, and that is placed longitudinally to be directly orindirectly in contact with a side wall surface of the heat sink so thata vertical line to each semiconductor chip surface is non-parallel tothe center line of the shaft; capacitors connected in parallel between aline from power supplying sides of the semiconductor modules to a powersupply and a line from grounding sides of the semiconductor modules to aground; and a choke coil disposed in a power line from the power supplyfor the semiconductor modules and disposed on a radially inner side of aside wall of the heat sink, and wherein the semiconductor modules, theheat sink and the capacitors are arranged to overlap one another atleast partly in the center line direction, and the semiconductormodules, the heat sink and the choke coil are arranged to overlap oneanother at least partly in the center line direction.
 2. The driveapparatus according to claim 1, wherein: the heat sink includes aplurality of side wall surfaces that define mutually different planes;and the semiconductor modules are dispersedly disposed on two or moreside wall surfaces out of the plurality of side wall surfaces; and thechoke coil is disposed in a space formed between the side wall surfacesof the heat sink.
 3. The drive apparatus according to claim 2, wherein:the heat sink includes a first side wall provided with the semiconductormodules in correspondence to a first driving system, and a second sidewall provided with the semiconductor modules in correspondence to asecond driving system; and the side walls are disposed to be symmetricalto each other with a center of the shaft as a reference.
 4. The driveapparatus according to claim 2, wherein: the heat sink is configured sothat the side wall surface thereof is tilted with respect to the centerline of the shaft.
 5. The drive apparatus according to claim 1, wherein:the capacitors are disposed on one sides of the semiconductor modules,which are same sides as the heat sink is; and the capacitors areaccommodated in accommodation spaces formed in the heat sink.
 6. Thedrive apparatus according to claim 1, wherein: the capacitors aredisposed on one sides of the semiconductor modules, which are oppositeto other sides of the semiconductor modules facing the heat sink.
 7. Thedrive apparatus according to claim 1, wherein: the heat sink includes aplurality of side walls that are separated from each other; and thesemiconductor modules are disposed to correspond to a plurality ofdriving systems, and disposed on the side walls so that one side wallcorresponds to one driving system.
 8. The drive apparatus according toclaim 7, wherein: the side walls each have connection portions, each ofwhich has a connecting hole that penetrates in an axial direction, onedges thereof.
 9. The drive apparatus according to claim 8, wherein: theheat sink includes a first side wall provided with the semiconductormodules in correspondence to a first driving system, and a second sidewall provided with the semiconductor modules in correspondence to asecond driving system; and the side walls are disposed to be symmetricalto each other with a center of the shaft as a reference.
 10. The driveapparatus according to claim 1, wherein: the electronic control unitincludes a control circuit that controls the semiconductor modules; thecontrol circuit is formed with a printed circuit board disposed in thecenter line direction of the shaft in the motor case; the printedcircuit board is disposed on one sides of the semiconductor modules,which are opposite to the motor case in the center line direction; thesemiconductor modules have control terminals at one ends thereof in thecenter line direction of the shaft, and the control terminals areconnected to the printed circuit board; and the semiconductor moduleshave coil terminals at other ends thereof, which are opposite to theprinted circuit board, and the coil terminals are connected to thewindings of the stator.
 11. The drive apparatus according to claim 1,wherein: the electronic control unit includes a control circuit thatcontrols the semiconductor modules; the control circuit is formed with aprinted circuit board disposed in the center line direction of the shaftin the motor case; the printed circuit board is disposed on one sides ofthe semiconductor modules, which are same sides as the motor case is inthe center line direction; the semiconductor modules have controlterminals at one ends thereof in the center line direction of the shaft,and the control terminals are connected to the printed circuit board;and the semiconductor modules have coil terminals at other ends thereof,which are opposite to the printed circuit board, and the coil terminalsare connected to the windings of the stator.
 12. The drive apparatusaccording to claim 11, wherein: the coil terminals are bent in radialdirections, and are connected to the windings of the stator by utilizingaccommodation spaces provided in the radial directions near thesemiconductor modules.
 13. The drive apparatus according to claim 12,wherein: the accommodation spaces near the semiconductor modules areprovided on the radially outer sides of the semiconductor modules. 14.The drive apparatus according to claim 1, wherein: specific ones of theplurality of semiconductor modules are preliminarily interconnectedthrough a bus bar to form a module unit.
 15. The drive apparatusaccording to claim 1, wherein: the heat sink is integrally formed with asame material as that of the motor case.
 16. The drive apparatusaccording to claim 1, wherein: the heat sink is configured so that theside wall surface thereof is tilted with respect to the center line ofthe shaft.
 17. The drive apparatus according to claim 16, wherein: theside wall surface is tilted to approach the center line of the shaft asdistanced away from an end of the motor case.
 18. The drive apparatusaccording to claim 16, wherein: the side wall surface is tilted torecede from the center line of the shaft as distanced away form an endof the motor case.
 19. The drive apparatus according to claim 1,wherein: a specific one of the plurality of semiconductor modulesincludes a semiconductor chip forming a semiconductor switching elementfor protection of the switching elements from reverse connection. 20.The drive apparatus according to claim 1, wherein: the plurality ofsemiconductor modules have terminals, which are dedicated to thecapacitors in the center line direction; and the capacitors are disposedto have the terminals thereof connected directly to the dedicatedterminals.